Dental composition, method of producing and use thereof

ABSTRACT

The invention relates to a dental composition having
     a) compound (A) with the following features:   only one backbone unit (U) with 6 to 20 carbon atoms, at least 6 carbon atoms thereof forming an aromatic or an aliphatic cyclic moiety, the remaining carbon atoms either being part of substituents pending from the cyclic moiety or being part of bridging groups to spacer units, wherein one or more of the remaining carbon atoms can be replaced by an oxygen atom, the backbone unit not comprising a bisphenol structure,   one or two spacer unit(s) (S) being connected to the backbone unit (U) via an ether linkage, at least one spacer unit (S) having a —CH2-CH2-CH2-CH2-O—CH2-CH(Q)-OG chain or a —CH2-CH(OG)-CH2-OM residue or a mixture of these two types of spacers within one spacer unit,   with G having at least one group selected from acroyl, methacroyl, acetyl, benzoyl, and combinations thereof, M having at least one aryl group, and combinations thereof, Q having at least one group selected from hydrogen, methyl, phenyl, phenoxymethyl, and combinations thereof,   b) filler (B) and c) initiator (C).

FIELD OF THE INVENTION

The invention relates to a composition comprising a hardenable compound, which contains a comparable rigid backbone unit, a spacer unit and a unit comprising polymerizable endgroups being connected to the spacer.

This composition is useful in the dental field and can be used for providing e.g. composite materials with reduced brittleness.

BACKGROUND ART

High durability of dental composite materials is sometimes desired to ensure appropriate performance. In case of high strength dental filling materials high brittleness can cause failures like e.g. cracks within the restauration so that a repair or a replacement might be necessary. In case of temporary materials, especially temporary crown and bridge materials, brittleness may lead to fracture of the material so that the material has to be replaced.

Typical physical parameters for determining brittleness of a material are E-modulus, elongation at break, and impact strength.

Various attempts were undertaken to address this issue.

WO 01/44338 relates to dental composites based on (meth)acrylates comprising certain urethane pre-polymers to reduce brittleness indicated by improved impact strength of the cured composition.

WO 2009/006282 relates to dental composites based on polyfunctional (meth)acrylates comprising urethane, urea or amide groups to reduce brittleness indicated by improved Impact Strength of the cured composition.

U.S. Pat. No. 7,534,909 (Otsjui et al.) relates to a (meth)acrylic ester compound having a specific formula. It is stated that the compound can be used in dental materials and optical parts.

JP 63 248811 (Mitshubishi) describes compositions with high refractive index useful for optical lenses, wherein the polymerizable components used contain halogenated aryl moieties.

However, there is still room for improvement especially with regard to the requirements to be fulfilled with respect to modern dental materials.

Thus, there is still a need for an improved dental composition, which can be used inter alia as a filling material or temporary or long term crown and bridge material.

DESCRIPTION OF THE INVENTION

An object which can be addressed by the invention is the provision of a composition having advantageous properties e.g. with respect to reduced brittleness.

In one embodiment the present invention features a dental composition or a composition for use in the dental area comprising

a) compound (A) with the following features:

-   -   only one backbone unit (U) with 6 to 20 carbon atoms, at least 6         carbon atoms thereof forming an aromatic or an aliphatic cyclic         moiety, the remaining carbon atoms either being part of         substituents pending from the cyclic moiety or being part of         bridging groups to spacer units, wherein one or more of the         remaining carbon atoms can be replaced by an oxygen atom, the         backbone unit not comprising a bisphenol structure,     -   one or two spacer unit(s) (S) being connected to the backbone         unit (U) via an ether linkage, at least one spacer unit (S)         comprising a —CH2-CH2-CH2-CH2-O—CH2-CH(Q)-OG chain or a         —CH2-CH(OG)-CH2-OM residue or a mixture of these two types of         spacers within one spacer unit,     -   with     -   G comprising at least one group selected from acroyl,         methacroyl, acetyl, benzoyl, mixtures and combinations thereof,     -   M comprising at least one aryl group, mixtures and combinations         thereof,     -   Q comprising at least one group selected from hydrogen, methyl,         phenyl, phenoxymethyl, mixtures and combinations thereof,     -   especially with the proviso that at least two G groups are         present in compound (A), wherein in the case where only one         spacer unit (S) is present, the G group not being part of said         spacer unit (S) is located in another substituent pending from         the aromatic or aliphatic cyclic moiety,         b) filler (B) and         c) initiator (C).

The invention also relates to a process of producing the dental composition comprising a mixing step.

According to another embodiment, the invention relates to the use of the composition as described in the present text as or for producing a dental cement, a crown and bridge material, a dental filling material, a casting material, a cavity liner, a coating composition, a mill blank, an orthodontic devices, a sealant or combinations thereof.

The invention is also directed to a kit or parts comprising at least 2 compositions as described in the present text, the compositions differ from each other at least with respect to their colour.

The invention is also directed to a process of using compound (A) as or for the production of a dental composition, the process typically comprising the steps of:

a) placing the composition comprising compound (A) in contact with a surface, b) hardening the composition.

DEFINITIONS

Within the description of the invention, the following terms are defined as follows:

The term “visible light” is used to refer to light having a wavelength of about 400 to about 800 nanometers (nm).

A “dental composition” is any composition which can or is to be used in the dental area. In this respect the composition should be not detrimental to the patients' health and thus free of hazardous and toxic components being able to migrate out of the composition. Examples of dental compositions include permanent and temporary crown and bridge materials, artificial crowns, dental filling materials, adhesives, casting materials, dental cements, cavity liners, coating compositions, sealants, mill blanks, lab materials and orthodontic devices.

Dental compositions are typically hardenable compositions, which can be hardened at ambient conditions, including a temperature range from about 15 to 50° C. or from about 20 to 40° C. within a time frame of about 30 min or 20 min or 10 min.

Higher temperatures are not recommended as they might cause pain to the patient and may be detrimental to the patient's health.

Dental compositions are typically provided to the practitioner in comparable small volumes, that is volumes in the range from about 0.1 to about 100 ml or from about 0.5 to about 50 ml or from about 1 to about 30 ml.

A “monomer” is any chemical substance which can be characterized by a chemical formula, bearing polymerizable groups (including (meth)acrylate groups) which can be polymerized to oligomers or polymers thereby increasing the molecular weight. The molecular weight of monomers can usually simply be calculated based on the chemical formula given.

A “hardenable compound or material” is any compound which can be cured or solidified e.g. by heating to cause polymerization, chemical crosslinking, radiation-induced polymerization or crosslinking or using a redox initiator. A hardenable compound may contain only two, three or more polymerizable groups. Typical examples of polymerizable groups include epoxy groups and unsaturated carbon groups, such as a vinyl group being present i.a. in a (methyl)acrylate group.

A “resin” contains all hardenable compounds (monomers, oligomers and/or polymers) being present in the hardenable composition. The resin may contain only one hardenable compound or a mixture of different hardenable compounds.

A “filler” contains all fillers being present in the hardenable composition. Only one type of filler or a mixture of different fillers can be used.

“Dispersed within the resin” means that filler particles are present in the resin as discrete, unassociated (i.e. non-agglomerated and non-aggregated) particles.

A “nano-sized filler” is a filler, the individual particles thereof have a size in the region of nanometers, e.g. an average particle diameter of less than about 200 nm. Useful examples are given in U.S. Pat. No. 6,899,948 and U.S. Pat. No. 6,572,693, the content of which especially with regard to nano-sized silica particles is herein incorporated by reference.

An “initiator or initiator system” is a substance being able to start the curing process of a hardenable compound.

A “curing, hardening or setting reaction” is used interchangeable and refers to a reaction wherein physical properties such as viscosity and hardness of a composition changes over the time due to a chemical reaction between the individual components.

A “derivative” is a chemical compound showing a chemical structure closely related to the corresponding reference compound and containing all featured structural elements of the corresponding reference compound but having small modifications like bearing in addition comparably small additional chemical groups like e.g. CH₃, Br, Cl, or F or not bearing comparably small chemical groups like e.g. CH₃ in comparison to the corresponding reference compound. The following examples might illustrate this: tetramethyl bis-phenol A bearing four additional methyl groups with respect to the reference compound bis-phenol A, and bis-phenol F not bearing two additional methyl groups with respect to the reference compound bis-phenol A are derivatives of bis-phenol A within the meaning of this definition.

“Ambient conditions” mean the conditions which the inventive composition is usually subjected to during storage and handling. Ambient conditions may, for example, be a pressure of about 900 to about 1100 mbar, a temperature of about −10 to about 60° C. and a relative humidity of about 10 to about 100%. In the laboratory ambient conditions are adjusted to about 23° C. and about 1013 mbar. In the dental and orthodontic field ambient conditions are reasonably understood as a pressure of about 950 to about 1050 mbar, temperature of about 15 to about 40° C. and relative humidity of about 20 to about 80%.

As used herein, “a”, “an”, “the”, “at least one” and “one or more” are used interchangeably. The terms “comprises” or “contains” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

Unless otherwise indicated, all numbers expressing quantities of ingredients, measurement of properties such as contrast ratio and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.”

DETAILED DESCRIPTION OF THE INVENTION

The inventive composition is typically a polymerizable composition. That is, the composition typically—but not necessarily—contains polymerizable components or compounds.

The invention also relates to a composition obtained or obtainable by polymerizing or curing the polymerizable composition.

According to one embodiment, the composition comprises compound (A) containing polymerizable moieties.

According to another embodiment, the composition comprises compound (A) not containing polymerizable moieties and a further compound comprising polymerizable moieties.

Thus, if the composition is a polymerizable composition it comprises compound (A) with the proviso that if compound (A) does not comprise polymerizable moieties, the composition comprises in addition a compound comprising polymerizable moieties.

The inventive composition is beneficial for the dentist in a couple of aspects.

E.g., it was found that compound (A) being contained in the inventive composition typically contributes to at least one or more of the following properties:

-   a) Compound (A) typically has a good (filler or pigment)     wettability. This may be beneficial to achieve comparably high     filler loads, if desired. -   b) Compound (A) typically has a comparably low viscosity. This may     be beneficial to achieve appropriate handling of the final     composition, if desired. It can also be beneficial to increase the     filler load, if desired, as the viscosity of the final composition     will typically be in an acceptable range. -   c) Compound (A) typically has a comparably high refractive index.     This may be beneficial to achieve appropriate ethetics and/or high     depth of cure for light curing materials, if desired. -   d) Compound (A) typically has a comparably high hydrophobicity. This     may be beneficial to achieve comparably low water uptake and/or     exogenic staining, if desired. -   e) Compound (A) can be used to provide compositions showing reduced     brittleness of the cured composition (i.e. a comparably high impact     strength and/or a medium E-modulus). This may be beneficial if the     risk of failures due to cracks and/or breaking should be reduced. -   f) Compound (A) can be used to provide compositions showing high     depth of cure. This may be beneficial if a bulk cure application of     light curing materials is desired. -   g) Compound (A) typically shows a medium E-modulus at standard wear     resistance (measured according to ACTA). This may be beneficial if a     comparably low brittleness is desired.

One or more of these properties can be obtained by using a compound having a comparable rigid backbone unit and a flexible spacer unit of a certain length.

The combination of appropriate mechanical properties like medium E-Modulus, high impact strength, and sufficient depth of cure (e.g. for light curing compositions) has been proven to beneficial, especially in the dental area.

Without wishing to be bound to a certain theory, it is assumed that the nature and length of the spacer units contribute to influence the flexibility and/or viscosity of the compound.

The rigid backbone containing a cyclic carbon moiety may contribute to the hydrophobicity.

Thus, compound (A) shows a unique combination of features which can help to provide a dental composition having advantageous properties, especially showing reduced brittleness of the cured composition.

Compound (A) can be characterized by the following features.

-   -   only one backbone unit (U) with 6 to 20 carbon atoms, at least 6         carbon atoms thereof forming an aromatic or an aliphatic cyclic         moiety, the remaining carbon atoms either being part of         substituents pending from the cyclic moiety or being part of         bridging groups to spacer units, wherein one or more of the         remaining carbon atoms can be replaced by an oxygen atom, the         backbone unit not comprising a bisphenol structure,     -   one or two spacer unit(s) (S) being connected to the backbone         unit (U) via an ether linkage, at least one spacer unit (S)         comprising a —CH2-CH2-CH2-CH2-O—CH2-CH(Q)—OG chain or a         —CH2-CH(OG)-CH2-OM residue or a mixture of these two types of         spacers within one spacer unit (wherein an example of such a         mixture is shown in the structure S3 below),     -   with     -   G comprising at least one group selected from acroyl,         methacroyl, acetyl, benzoyl, and mixtures thereof,     -   M comprising at least one aryl group, and mixtures thereof,     -   Q comprising at least one group selected from hydrogen, methyl,         phenyl, phenoxymethyl, and mixtures thereof.

At least two G groups are present in compound (A), wherein in the case where only one spacer unit (S) is present, the G group not being part of said spacer unit (S) is located in a substituent pending from the aromatic or aliphatic cyclic moiety.

The term “backbone unit” means a unit, which forms a central part of compound (A). In order to function as a backbone unit, the backbone unit has to be at least bi-functional or divalent. That is, at least two, three or four substituents are attached to the backbone unit. A unit, which contains only one substituent cannot be regarded as a backbone unit. Such a unit is rather understood as a pending substituent itself.

The backbone unit (U) comprises at least two substituents, which can be same or different, wherein each substituent comprises a polymerizable moiety. Thus, the at least two polymerizable moieties are present in two different substituents attached to the backbone unit (U).

Alternatively or in other words, compound (A) comprises at least two G groups, which can be same or different, wherein—in the case where only one spacer unit (S) is present—the G group not being part of said spacer unit (S) is located in a substituent pending from the aromatic or aliphatic cyclic moiety.

The term “bisphenol structure” includes structures like bisphenol A, bisphenol AP (4,4′-(1-Phenylethylidene)bisphenol), bisphenol C (Bis(4-hydroxyphenyl)-2,2-dichloroethylene), bisphenol F (Bis(2-Hydroxyphenyl)methane), bisphenol TMC (4,4′-(3,3,5-Trimethyl-cyclohexylidene)bisphenol). These and other abbreviations are known to the person skilled in the art.

If desired, different compounds falling within the definition of compound (A) can be present in the composition. E.g. the inventive composition may contain two, three, four or even more compounds, which differ from each other e.g. by the nature of the backbone unit and/or the nature of the spacer unit(s).

Compound (A) can typically be characterized by at least one, two, three, four or five of the following features:

-   a) Molecular weight (Mw): from about 550 to about 1000; -   b) Reactive Functionality: about 2, exactly 2 or not more than 2     ethylenically unsaturated reactive groups per molecule attached via     an ester linkage onto the backbone; -   c) Non Reactive Functions: about 2, exactly 2 or not more than 2     hydrocarbon non reactive groups per molecule attached via an ester     linkage onto the backbone; -   d) Polar Groups: essentially no free OH groups within the molecule; -   e) Secondary Network: essentially no urethane moieties within the     molecule; -   f) Refractive index: from about 1.495 to about 1.565 (n_(D) ²⁰).

Thus, compound (A) can be characterized as described in the present text and further by fulfilling at least one of the features a), b), c), d), e) or f).

E.g. according to one embodiment, compound (A) fulfils e.g. features a), b) and c). According to another embodiment, compound (A) fulfils e.g. features a), b) and d). According to a further embodiment, compound (A) fulfils e.g. features a), b), d) and e).

The backbone unit (U) may comprise a moiety selected from

wherein the symbol “*” indicates connecting points of the molecular fragment.

The spacer unit(s) (S) may comprise a moiety selected from

S1:

-   -   with m=1 to 3 and n=1 to 3,     -   Q=hydrogen, methyl, phenyl, phenoxymethyl,

S2:

-   -   with M=aryl or phenyl,

S3:

-   -   with m=1 to 3 and n=1 to 3,     -   Q=hydrogen, methyl, phenyl, phenoxymethyl and     -   M=aryl or phenyl.

“G” may comprise a moiety selected from

and, combinations and mixtures thereof.

The symbol “*” indicates connecting points of the molecular fragments to other fragments. That is, two fragments each bearing a “*” can be connected to each other via a chemical bond.

Aryl means a moiety comprising 6 to 9 carbon atoms, including alkyl (C1 to C3) substituted phenyl moieties. Moieties like naphtyl or biphenyl are not comprised.

According to a specific embodiment, compound (A) may be characterized by a structure according to any of formulas (I), (II), and (III)

-   -   with     -   a, b=0 to 3, c, d=0 to 3, (a+b)=1 to 6, (c+d)=1 to 6,

Q=being independently selected from hydrogen, methyl, phenyl or phenoxymethyl,

-   -   with     -   a, b=0 to 3, c, d=0 to 3, (a+b)=1 to 6, (c+d)=1 to 6,

Q=being independently selected from hydrogen, methyl, phenyl or phenoxymethyl, wherein G is selected from

and wherein U is selected from

combinations and mixtures thereof.

With respect to any of the formulas (I) to (III), “U” and “G” can be any of the moieties outlined in the text above in connection with the description of “U” and “G”.

Compound (A) is typically present in the composition in an amount of at least about 5 wt.-% or at least about 10 wt.-% or at least about 20 wt.-%.

The amount of compound (A) contained in the composition is typically up to about 50 wt.-% or up to about 60 wt.-% or up to about 70 wt.-%.

Typical ranges include from about 5 to about 70 or from about 10 to about 60 or from about 10 to about 45 or from about 10 to about 30 wt.-%.

Compound (A) can be obtained or produced e.g. by the following process:

reacting e.g. alcohols (like e.g. TCD alcohol or ethoxylated resorcinol (ER) or ethoxylated hydroquinone (EH)) with epoxies (like e.g. glycidyl phenyl ether (GP)) or with epoxy moieties containing mixtures (like e.g. ethyleneoxide (EO) in THF or propyleneoxide (PO) in THF or styreneoxide (SO), or GP in THF) in a solvent (like e.g. tetrahydrofurane (THF)), thereby obtaining an ether derivative; reacting the ether derivative obtained with e.g. methacrylic acid (MA) or acrylic acid (AA) or acetic acid anhydride (AAA) or benzoic acid (BA) to form the corresponding esters.

Compound (A) can also be obtained or produced e.g. by the following process:

reacting an OH acidic compound (like e.g. phenol, resorcinol) with epoxies (like e.g. resorcinol diglycidylether (RDGE) or cyclohexane-1,4-dimethanole diglycidylether (CDGE)), thereby obtaining an ether derivative; reacting the ether derivative obtained with e.g. methacrylic acid (MA) or acrylic acid (AA) or acetic acid anhydride (AAA) or benzoic acid (BA) to form the corresponding esters.

The reaction of alcohols with epoxies can be carried out using a basic catalyst (especially e.g. for the reaction of alcohols with epoxies (like e.g. GP), or using a Lewis acidic catalyst (especially e.g. for the reaction of alcohols with epoxy containing mixtures (like e.g. EO in THF)).

The reaction of OH acidic compounds with epoxids can be carried out using e.g. a moderate nucleophilic catalyst or a basic catalyst.

Examples for basic catalysts include triethylamine (TEA), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), triethylammonium acetate (TEAA), sodium acetate (NaOAc), potassium acetate (KOAc), potassium tert-butoxide (KOtBu) and mixtures thereof.

Examples for Lewis acidic catalyst include boron trifluoride etherates i.e. BF₃*THF, BF₃*OEt₂ and mixtures thereof.

Examples for nucleophilic catalyst include triphenylphosphane (PPh₃).

The reaction can typically be carried out in a temperature range of about 40 to about 110° C., typically under dry conditions and a protective gas atmosphere (i.e. under the exclusion of water and oxygen). The reaction can be carried out in common solvents including hexane, cyclohexane, methylcyclohexane, toluene, ethyl acetate, diethylether, methyl-tert-butyl-ether, tetrahydrofurane and mixtures thereof or without a solvent.

If desired, the crude reaction product(s) can be treated with organic acids to reduce unwanted discolorations.

The esterification reaction can be carried out in a temperature range of about 60 to about 110° C., preferably under air, using common reaction procedures like e.g. acid catalyzed esterification with removal of water using a Dean Starck apparatus. The reaction can be carried out in common solvents including hexane, cyclohexane, methylcyclohexane, toluene, methyl-tert-butyl-ether and mixtures thereof.

By choosing appropriate molar ratios of the reactive components (i.e. educts), the desired molecular structure of the reaction product can be adjusted.

In an ideal case, if for example a di-functional alcohol (HO—X—OH) is reacted with one equivalent of Y, the final reaction product will typically contain a statistical mixture of the following components in the respective amounts: HO—X—OH (25%), Y—O—X—O—Y (25%), Y—O—X—OH (50%).

In an ideal case, if for example a di-functional alcohol (HO—X—OH) is reacted with two equivalent of Y, the final reaction product will typically contain Y—O—X—O—Y (100%).

If desired, further purification of the product mixture can be achieved by means known to the skilled person including HPLC, distillation and fractionized crystallisation.

To prevent unwanted radical polymerization during the synthesis, a stabilizer in an appropriate amount (e.g. about 50 to about 500 ppm) such as 3,5-di-tert.-butyl-4-hydroxy-toluene (BHT), 4-methoxyphenol (MOP), or hydroquinone (HQ) can be used, if desired.

If desired, compound (A) can be combined with surface treated SiO2 and/or ZrO2 nano particles to obtain dispersions of surface treated SiO2 and/or ZrO2 nano particles within compound (A).

The inventive composition may comprise a filler or a filler matrix. The filler matrix can be comprised of one filler or a mixture of different fillers.

The nature of filler of the inventive composition is not particularly limited. The size of the filler particles should be such that a homogeneous mixture with the hardenable component(s) forming the resin matrix can be obtained.

Useful fillers include fumed silica, fillers based on fluoroaluminosilicate glasses, quartz, ground glasses, non-water-soluble fluorides such as CaF₂, silica gels such as silicic acid, in particular pyrogenic silicic acid and granulates thereof, cristobalite, calcium silicate, zirconium silicate, zeolites, including the molecular sieves, metal oxide powders, such as aluminium or zinc oxides or their mixed oxides, barium sulphate, yttrium fluoride, calcium carbonate.

The silica is usually dispersed within the resin matrix. The silica particles used in the dental compositions of the invention preferably have an average diameter of less than about 200 nm; more preferably, the particles are less than about 100 nm in average diameter. These measurements are preferably based on a TEM (transmission electron microscopy) method, whereby a population is analyzed to obtain an average particle diameter. A preferred method for measuring the particle diameter can be described is as follows:

Samples approximately 80 nm thick are placed on 200 mesh copper grids with carbon stabilized formvar substrates (SPI Supplies—a division of Structure Probe, Inc., West Chester, Pa.). A transmission electron micrograph (TEM) is taken, using JEOL 200CX (JEOL, Ltd. of Akishima, Japan and sold by JEOL USA, Inc.) at 200 Kv. A population size of about 50-100 particles can be measured and an average diameter is determined.

The average surface area of the silica particles is preferably greater than about 15 m²/g more preferably greater than about 30 m²/g.

Once dispersed in the resin, the silica particles are in a discrete (individual) and unassociated (i.e. non-agglomerated, non-aggregated) condition. “Agglomerated” as used herein, is descriptive of a weak association of particles usually held together by charge or polarity and can be broken down into smaller entities. “Aggregated,” as used herein, is descriptive of a strong association of particles often bound together by, for example, residual chemicals treatment; further breakdown of the aggregates into smaller entities is very difficult to achieve.

The silica particles which can be used in the dental materials of the invention are preferably substantially spherical and substantially non-porous. Although the silica is preferably essentially pure, it may contain small amounts of stabilizing ion such as ammonium and alkaline metal ions.

Suitable fumed silicas include for example, products sold under the tradename AEROSIL series OX-50, -130, -150, and -200 available from Degussa AG, (Hanau, Germany), and CAB-O-SIL M5 available from Cabot Corp (Tuscola, Ill.).

Useful fluoroaluminosilicate glasses include silanol treated fluoroaluminosilicate glass fillers, as described in U.S. Pat. No. 5,332,429, the disclosure of which is expressly incorporated by reference herein. For example, a fluoride releasing glass may be added to the dental composition to provide the benefit of long-term release of fluoride in use, for example in the oral cavity.

Optionally, a heavy metal oxide can be included in the dental materials of the invention to provide a radiopaque dental material. It is preferred that the heavy metal oxide be present in an amount effective to impart radiopacity. As used herein, “radiopacity” describes the ability of a hardened dental material to be distinguished from tooth structure using standard dental X-ray equipment in the conventional manner. Radiopacity in a dental material is advantageous in certain instances where X-rays are used to diagnose a dental condition. For example, a radiopaque material would allow the detection of secondary caries that may have formed in the tooth tissue surrounding a filling. The desired degree of radiopacity can be varied, depending upon the particular application and the expectations of the practitioner evaluating the X-ray film.

Oxides of heavy metals having an atomic number greater than about 28 can be preferred. The heavy metal oxide should be chosen such that undesirable colors or shading are not imparted to the hardened resin in which it is dispersed. For example, iron and cobalt would not be favoured, as they impart dark and contrasting colors to the neutral tooth color of the dental material. More preferably, the heavy metal oxide is an oxide of metals having an atomic number greater than 30. Suitable metal oxides are the oxides of yttrium, strontium, barium, zirconium, hafnium, niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanide elements (i.e. elements having atomic numbers ranging from 57 to 71, inclusive), cerium and combinations thereof. Most preferably, the oxides of heavy metals having an atomic number greater than 30, but less than 72 are optionally included in the materials of the invention. Particularly preferred radiopacifying metal oxides include lanthanum oxide, zinc oxide, tin oxide, zirconium oxide, yttrium oxide, ytterbium oxide, barium oxide, strontium oxide, cerium oxide, and combinations thereof. The heavy metal oxide particles may be aggregated. If so, it is preferred that the aggregated particles are less than about 200 nm, and more preferably are less than about 90 nm in average diameter.

In a preferred embodiment the filler matrix comprises a nano-sized filler including nano-sized silica.

Preferred nano-sized silicas are commercially available from Nalco Chemical Co. (Naperville, Ill.) under the product designation NALCO COLLOIDAL SILICAS (for example, preferred silica particles can be obtained from using NALCO products 1040, 1042, 1050, 1060, 2327 and 2329), Nissan Chemical America Company, Houston, Tex. (for example, SNOWTEX-ZL, -OL, -O, -N, -C, -20L, -40, and -50); Admatechs Co., Ltd., Japan (for example, SX009-MIE, SX009-MIF, SC1050-MJM, and SC1050-MLV); Grace GmbH & Co. KG, Worms, Germany (for example, those available under the product designation LUDOX, e.g., P-W50, P-W30, P-X30, P-T40 and P-T40AS); Akzo Nobel Chemicals GmbH, Leverkusen, Germany (for example, those available under the product designation LEVASIL, e.g., 50/50%, 100/45%, 200/30%, 200A/30%, 200/40%, 200A/40%, 300/30% and 500/15%), and Bayer MaterialScience AG, Leverkusen, Germany (for example, those available under the product designation DISPERCOLL S, e.g., 5005, 4510, 4020 and 3030). In a preferred embodiment where the hardenable resin employs a cationic initiation system, the starting silica is preferably acidic (such as Nalco 1042).

Surface-treating the nano-sized silica particles before loading into the dental material can provide a stable dispersion in the resin. “Stable”, as used herein, means a dental material in which the particles do not agglomerate after standing for a period of time, such as about 24 hours, under standard ambient conditions, e.g. room temperature (about 20 to about 22° C.), atmospheric pressure, and no extreme electromagnetic forces. Preferably, the surface-treatment stabilizes the nano-sized particles so that the particles will be well dispersed in the hardenable resin and results in a substantially homogeneous composition. Furthermore, it is preferred that the silica be modified over at least a portion of its surface with a surface treatment agent so that the stabilized particle can copolymerize or otherwise react with the hardenable resin during curing.

The silica particles can be treated with a resin-compatibilizing surface treatment agent. Particularly preferred surface treatment or surface modifying agents include silane treatment agents capable of polymerizing with a resin. Preferred silane treatment agent include γ-methacryloxypropyltrimethoxysilane, available commercially under the trade designation A-174, available commercially from Witco OSi Specialties (Danbury, Conn.) and γ-glycidoxypropyltrimethoxy silane, a product available under the trade designation G6720, available from United Chemical Technologies (Bristol, Pa.).

Alternatively a combination of surface modifying agents can be useful, wherein at least one of the agents has a functional group co-polymerizable with a hardenable resin. For example, the polymerizing group can be ethylenically unsaturated or a cyclic function subject to ring opening polymerization. An ethylenically unsaturated polymerizing group can be, for example, an acrylate or methacrylate, or vinyl group. A cyclic functional group subject to ring opening polymerization generally contains a heteroatom such as oxygen, sulfur or nitrogen, and preferably is a 3-membered ring containing oxygen such as an epoxide. Other surface modifying agents which do not generally react with hardenable resins can be included to enhance dispersibility or rheological properties. Examples of silane of this type include, for example, alkyl or aryl polyethers, alkyl, hydroxy alkyl, hydroxy aryl, or amino alkyl functional silanes.

Upon surface treating the silica particles, they can then be combined with an appropriate hardenable resin to form a dental composition of the invention.

The filler matrix can comprise at least about 25 wt.-% or at least about 30 wt.-% or at least about 40 wt.-% or at least about 50 wt.-% of the whole composition.

The amount of filler to be used in the filler matrix usually depends on the purpose for which the composition should be used.

The filler matrix can comprise up to about 90 wt.-% or up to about 85 wt.-% or up to about 80 wt.-% or up to about 75 wt.-% of the whole composition.

Temporary crown and bridge materials (as an example for a dental composition) usually do not contain a high amount of fillers. With respect to these compositions, the filler content usually is in a range of about 30 to about 60 wt.-% with respect to the whole composition.

In dental filling materials (as an example of a dental composition; sometimes also referred to as dental composite materials), which typically contain a higher amount of fillers compared to temporary crown and bridge materials, the filler content is usually in a range of about 60 to about 85 wt.-% with respect to the whole composition.

The inventive dental composition also comprises an initiator or initiator system being able to start the curing process of the hardenable components being present in the resin matrix.

Dental materials of the invention can be chemically curable, heat curable or light curable compositions. Light curable materials should have an appropriate initiator system. Chemically curable materials can be auto-cured (e.g. via redox initiators). Alternatively, the materials of the invention can be hardened by a combination of auto- and light-cure.

For free radical polymerization (hardening), an initiation system can be selected from systems which initiate polymerization via radiation, heat, or redox/auto-cure chemical reaction. A class of initiators capable of initiating polymerization of free radically active functional groups includes free radical-generating photoinitiators, optionally combined with a photosensitizer or accelerator. Such initiators typically can be capable of generating free radicals for addition polymerization upon exposure to light energy having a wavelength between about 200 and about 800 nm.

A variety of visible or near-IR photoinitiator systems may be used for photopolymerization of free-radically polymerizable materials useful in the invention. For example, in free radical polymerization (hardening), a photoinitiation system can be selected from systems which initiate polymerization via a two component system of an amine and an α-diketone as described in U.S. Pat. No. 4,071,424 and WO 2009151957, which are herein incorporated by reference. Alternatively, the resin can be combined with a three components or ternary photoinitiator system such as described in U.S. Pat. No. 5,545,676 and WO 2009151957, which are incorporated herein by reference.

In the ternary photoinitator system, the first component is an iodonium salt, i.e., a diaryliodonium salt. The iodonium salt is preferably soluble in the monomer and shelf-stable (ie., does not spontaneously promote polymerization) when dissolved therein in the presence of the sensitizer and donor. Accordingly, selection of a particular iodonium salt may depend to some extent upon the particular monomer, polymer or oligomer, sensitizer and donor chosen. Suitable iodonium salts are described in U.S. Pat. No. 3,729,313, U.S. Pat. No. 3,741,769, U.S. Pat. No. 3,808,006, U.S. Pat. No. 4,250,053 and U.S. Pat. No. 4,394,403, the iodonium salt disclosures of which are incorporated herein by reference. The iodonium salt can be a simple salt (e.g., containing an anion such as Cl⁻, Br⁻, I⁻ or C₄H₅ SO₃ ⁻) or a metal complex salt (e.g., containing SbF₆OH⁻ or AsF₆ ⁻). Mixtures of iodonium salts can be used if desired. Preferred iodonium salts include diphenyliodonium salts such as diphenyliodonium chloride, diphenyliodonium hexafluorophosphate and diphenyliodonium tetrafluoroborate.

The second component in a ternary photoinitiator system is a sensitizer. The sensitizer desirably is soluble in the monomer, and is capable of light absorption somewhere within the range of wavelengths of greater than 400 to 1200 nanometers, more preferably greater than 400 to 700 nanometers and most preferably greater than 400 to about 600 nanometers. The sensitizer may also be capable of sensitizing 2-methyl-4,6-bis(trichloromethyl)-s-triazine, using the test procedure described in U.S. Pat. No. 3,729,313, which is incorporated herein by reference. Preferably, in addition to passing this test, a sensitizer is also selected based in part upon shelf stability considerations. Accordingly, selection of a particular sensitizer may depend to some extent upon the particular monomer, oligomer or polymer, iodonium salt and donor chosen.

Suitable sensitizers can include compounds in the following categories: ketones, coumarin dyes (e.g., ketocoumarins), xanthene dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketone compounds, aminotriaryl methanes, merocyanines, squarylium dyes and pyridinium dyes. Ketones (e.g., monoketones or alpha-diketones), ketocoumarins, aminoarylketones and p-substituted aminostyryl ketone compounds are preferred sensitizers. For applications requiring high sensitivity, it is preferred to employ a sensitizer containing a julolidinyl moiety. For applications requiring deep cure (e.g., cure of highly-filled composites), it is preferred to employ sensitizers having an extinction coefficient below about 1000, more preferably below about 100, at the desired wavelength of irradiation for photopolymerization.

Alternatively, dyes that exhibit reduction in light absorption at the excitation wavelength upon irradiation can be used.

For example, a preferred class of ketone sensitizers has the formula: ACO(X)_(b) B, where X is CO or CR⁵, R⁶, where R⁵ and R⁶ can be the same or different, and can be hydrogen, alkyl, alkaryl or aralkyl, b is zero or one, and A and B different and can be substituted (having one or more non-interfering substituents) can be the same or or unsubstituted aryl, alkyl, alkaryl, or aralkyl groups, or together A and B can form a cyclic structure which can be a substituted or unsubstituted cycloaliphatic, aromatic, heteroaromatic or fused aromatic ring.

Suitable ketones of the above formula include monoketones (b=0) such as 2,2-, 4,4- or 2,4-dihydroxybenzophenone, di-2-pyridyl ketone, di-2-furanyl ketone, di-2-thiophenyl ketone, benzoin, fluorenone, chalcone, Michler's ketone, 2-fluoro-9-fluorenone, 2-chlorothioxanthone, acetophenone, benzophenone, 1- or 2-acetonaphthone, 9-acetylanthracene, 2-, 3- or 9-acetylphenanthrene, 4-acetylbiphenyl, propiophenone, n-butyrophenone, valerophenone, 2-, 3- or 4-acetylpyridine, 3-acetylcoumarin and the like. Suitable diketones include aralkyldiketones such as anthraquinone, phenanthrenequinone, o-, m- and p-diacetylbenzene, 1,3-, 1,4-, 1,5-, 1,6-, 1,7- and 1,8-diacetylnaphthalene, 1,5-, 1,8- and 9,10-diacetylanthracene, and the like. Suitable alpha-diketones (b=1 and X=CO) include 2,3-butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione, 3,4-heptanedione, 2,3-octanedione, 4,5-octanedione, benzil, 2,2′-3 3′- and 4,4′-dihydroxylbenzil, furil, di-3,3′-indolylethanedione, 2,3-bornanedione (camphorquinone), biacetyl, 1,2-cyclohexanedione, 1,2-naphthaquinone, acenaphthaquinone, and the like.

The third component of a ternary initiator system is a donor. Preferred donors include, for example, amines (including aminoaldehydes and aminosilanes), amides (including phosphoramides), ethers (including thioethers), ureas (including thioureas), ferrocene, sulfinic acids and their salts, salts of ferrocyanide, ascorbic acid and its salts, dithiocarbamic acid and its salts, salts of xanthates, salts of ethylene diamine tetraacetic acid and salts of tetraphenylboronic acid. The donor can be unsubstituted or substituted with one or more non-interfering substituents. Particularly preferred donors contain an electron donor atom such as a nitrogen, oxygen, phosphorus, or sulfur atom, and an abstractable hydrogen atom bonded to a carbon or silicon atom alpha to the electron donor atom. A wide variety of donors is disclosed in U.S. Pat. No. 5,545,676, which is incorporated herein by reference.

Alternatively, free-radical initiators useful in the invention include the class of acylphosphine oxides, as described in U.S. Pat. No. 4,737,593. Such acylphosphine oxides are of the general formula

(R⁹)₂—P(═O)—C(═O)—R¹⁹

wherein each R⁹ individually can be a hydrocarbyl group such as alkyl, cycloalkyl, aryl, and aralkyl, any of which can be substituted with a halo-, alkyl- or alkoxy-group, or the two R⁹ groups can be joined to form a ring along with the phosphorous atom, and wherein R¹⁹ is a hydrocarbyl group, an S-, O-, or N-containing five- or six-membered heterocyclic group, or a —Z—C(═O)—P(═O)— (R⁹)₂ group, wherein Z represents a divalent hydrocarbyl group such as alkylene or phenylene having from 2 to 6 carbon atoms.

Preferred acylphosphine oxides useful in the invention are those in which the R⁹ and R¹⁰ groups are phenyl or lower alkyl- or lower alkoxy-substituted phenyl. By “lower alkyl” and “lower alkoxy” is meant such groups having from 1 to 4 carbon atoms. Most preferably, the acylphosphine oxide is bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (IRGACURE™ 819, Ciba Specialty Chemicals, Tarrytown, N.Y.).

Tertiary amine reducing agents may be used in combination with an acylphosphine oxide. Illustrative tertiary amines useful in the invention include ethyl 4-(N,N-dimethylamino)benzoate and N,N-dimethylaminoethyl methacrylate.

Commercially-available phosphine oxide photoinitiators capable of free-radical initiation when irradiated at wavelengths of greater than 400 nm to 1200 nm include a 25:75 mixture, by weight, of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (IRGACURE™ 1700, Ciba Specialty Chemicals), 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholinophenyl)-1-butanone (IRGACURE™ 369, Ciba Specialty Chemicals), bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl) titanium (IRGACURE™ 784 DC, Ciba Specialty Chemicals), a 1:1 mixture, by weight, of bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropane-1-one (DAROCUR™ 4265, Ciba Specialty Chemicals), and ethyl-2,4,6-trimethylbenzylphenyl phosphinate (LUCIRIN™ LR8893X, BASF Corp., Charlotte, N.C.).

Another free-radical initiator system that can alternatively be used in the dental materials of the invention includes the class of ionic dye counterion complex initiators comprising a borate anion and a complementary cationic dye.

Borate salt photoinitiators are described, for example, in U.S. Pat. No. 4,772,530, U.S. Pat. No. 4,954,414, U.S. Pat. No. 4,874,450, U.S. Pat. No. 5,055,372, and U.S. Pat. No. 5,057,393, the disclosures of which are incorporated herein by reference.

Borate anions useful in these photoinitiators generally can be of the formula R¹R²R³R⁴B⁻, wherein R¹, R², R³, and R⁴ independently can be alkyl, aryl, alkaryl, allyl, aralkyl, alkenyl, alkynyl, alicyclic and saturated or unsaturated heterocyclic groups. Preferably, R², R³, and R⁴ are aryl groups and more preferably phenyl groups, and R¹ is an alkyl group and more preferably a secondary alkyl group.

Cationic counterions can be cationic dyes, quaternary ammonium groups, transition metal coordination complexes, and the like. Cationic dyes useful as counterions can be cationic methine, polymethine, triarylmethine, indoline, thiazine, xanthene, oxazine or acridine dyes. More specifically, the dyes may be cationic cyanine, carbocyanine, hemicyanine, rhodamine, and azomethine dyes. Specific examples of useful cationic dyes include Methylene Blue, Safranine O, and Malachite Green. Quaternary ammonium groups useful as counterions can be trimethylcetylammonium, cetylpyridinium, and tetramethylammonium. Other organophilic cations can include pyridinium, phosphonium, and sulfonium.

Photosensitive transition metal coordination complexes that may be used include complexes of cobalt, ruthenium, osmium, zinc, iron, and iridium with ligands such as pyridine, 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 1,10-phenanthroline, 3,4,7,8-tetramethyl-phenanthroline, 2,4,6-tri(2-pyridyl-s-triazine) and related ligands.

Yet another alternative class of initiators capable of initiating polymerization of free radically active functional groups includes conventional chemical initiator systems such as a combination of a peroxide and an amine. These initiators, which rely upon a thermal redox reaction, are often referred to as “auto-cure catalysts.” They are typically supplied as two-part systems in which the reactants are stored apart from each other and then combined immediately prior to use.

In a further alternative, heat may be used to initiate the hardening, or polymerization, of free radically active groups. Examples of heat sources suitable for the dental materials of the invention include inductive, convective, and radiant. Thermal sources should be capable of generating temperatures of at least 40° C. to 15° C. under normal conditions or at elevated pressure. This procedure is preferred for initiating polymerization of materials occurring outside of the oral environment.

Organic peroxide compounds together with so-called activators are also suitable as redox initiator systems. In particular, compounds such as lauroyl peroxide, benzoyl peroxide and p-chlorobenzoyl peroxide and p-methylbenzoyl peroxide can be considered as organic peroxide compounds.

Suitable as activators are, for example, tertiary aromatic amines, such as the N,N-bis-(hydroxyalkyl)-3,5-xylidines known from U.S. Pat. No. 3,541,068 as well as N,N-bis-(hydroxyalkyl)-3,5-di-t-butylanilines, in particular N,N-bis-([beta]-oxybutyl)-3,5-di-t-butylaniline as well as N,N-bis-(hydroxyalkyl)-3,4,5-trimethylaniline.

Well-suited activators are also the barbituric acids and barbituric acid derivatives as described in US 2003/008967, DE 14 95 520 as well as the malonyl sulfamides described in U.S. Pat. No. 4,544,742 (corresponding to EP 0 059 451). Preferred malonyl sulfamides are 2,6-dimethyl-4-isobutylmalonyl sulfamide, 2,6-diisobutyl-4-propylmalonyl sulfamide, 2,6-dibutyl-4-propylmalonyl sulfamide, 2,6-dimethyl-4-ethylmalonyl sulfamide and 2,6-dioctyl-4-isobutyl malonyl sulfamide.

For further acceleration, the polymerization is in this case preferably carried out in the presence of heavy-metal compounds and ionogenic halogen or pseudohalogen. The heavy metal is suitably used in the form of soluble organic compounds. Likewise, the halide and pseudohalide ions are suitably used in the form of soluble salts, as examples there can be named the soluble amine hydrochlorides as well as quaternary ammonium chloride compounds. Suitable accelerators are in particular metals from the iron or copper group, preferably copper and iron complexes and in particular copper complexes. The heavy metal is preferably employed in the form of soluble organic compounds. Suitable are, for example, iron carboxylates, copper carboxylates, iron procetonate, copper procetonate, copper naphthenate, copper acetate and iron naphthenate.

The initiator is typically present in the composition in an amount of at least about 0.1 wt.-% or at least about 0.2 wt.-% or at least about 0.3 wt.-%.

The amount of initiator contained in the composition is typically up to about 3 wt.-% or up to about 2 wt.-% or up to about 1.8 wt.-%.

Typical ranges include from about 0.1 to about 3 or from about 0.2 to about 2 or from about 0.3 to about 1.8 wt.-%.

According to another embodiment the composition can comprise a (further) polymerizable component (D) being different from compound (A). Component (D) is typically a free-radically polymerizable material, including ethylenically unsaturated monomer, monomers or oligomers or polymers.

Suitable polymerizable components contain at least one ethylenically unsaturated bond, and are capable of undergoing addition polymerization. Such free-radically polymerizable materials include mono-, di- or poly-acrylates and methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, isopropyl methacrylate, n-hexyl acrylate, stearyl acrylate, allyl acrylate, glycerol diacrylate, the diurethane dimethacrylate called UDMA (mixture of isomers, e.g. Röhm Plex 6661-0) being the reaction product of 2-hydroxyethyl methacrylate (HEMA) and 2,2,4-trimethylhexamethylene diisocyanate (TMDI), glycerol triacrylate, ethyleneglycol diacrylate, diethyleneglycol diacrylate, triethyleneglycol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, trimethylolpropane triacrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate, bis[1-(2-acryloxy)]-p-ethoxyphenyldimethylmethane, bis[1-(3-acryloxy-2-hydroxy)]-p-propoxyphenyl-dimethylmethane, and trishydroxyethyl-isocyanurate trimethacrylate; the bis-acrylates and bis-methacrylates of polyethylene glycols of molecular weight 200-500, copolymerizable mixtures of acrylated monomers such as those in U.S. Pat. No. 4,652,274, and acrylated oligomers such as those of U.S. Pat. No. 4,642,126; and vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate and divinylphthalate; polyfunctional (meth)acrylates comprising urethane, urea or amide groups, as those of EP 2007111356, herewith incorporated by reference. Mixtures of two or more of these free radically polymerizable materials can be used if desired.

If desired, the polymerizable material(s) may contain both cationically polymerizable and free-radically polymerizable functionalities in a single molecule. These may be obtained, for example, by reacting a di- or poly-epoxide with one or more equivalents of an ethylenically unsaturated carboxylic acid. Examples of such materials include the reaction product of UVR-6105 (available from Union Carbide) or DER 332 (available from Dow Chemical Co.) with one equivalent of methacrylic acid. Commercially available materials having epoxy and free-radically polymerizable functionalities include the “Cyclomer” series, such as Cyclomer M100 or M101, available from Daicel Chemical, Japan.

If present, component (D) is typically present in the composition in an amount of at least about 5 wt.-% or at least about 10 wt.-% or at least about 20 wt.-%.

If present, the amount of component (D) contained in the composition is typically up to about 45 wt.-% or up to about 55 wt.-% or up to about 65 wt.-%.

If present, typical ranges include from about 5 to about 65 or from about 10 to about 55 or from about 10 to about 40 or from about 10 to about 25 wt.-%.

The polymerizable material(s) can also contain a softener (E) not comprising polymerizable groups.

The softener (E) can comprise hydroxyl functionalities.

Preferably, the hydroxyl group containing material may contain two or more primary or secondary aliphatic hydroxyl groups (i.e., the hydroxyl group is bonded directly to a non-aromatic carbon atom). The hydroxyl groups can be terminally situated, or they can be pendent from a polymer or copolymer. The molecular weight of the hydroxyl-containing organic material can vary from very low (e.g., 32) to very high (e.g., one million or more). Suitable hydroxyl-containing materials can have low molecular weights, i.e. from about 32 to 200, intermediate molecular weight, i.e. from about 200 to 10,000, or high molecular weight, i.e. above about 10,000. As used herein, all molecular weights are weight average molecular weights.

The hydroxyl group containing material can optionally contain other functionalities that do not substantially interfere with cationic polymerization at room temperature. Thus, the hydroxyl group containing materials can be nonaromatic in nature or can contain aromatic functionality. The hydroxyl-containing material can optionally contain heteroatoms in the backbone of the molecule, such as nitrogen, oxygen, sulfur, and the like, provided that the ultimate hydroxyl-containing material does not substantially interfere with cationic polymerization at room temperature. The hydroxyl group containing material can, for example, be selected from naturally occurring or synthetically prepared cellulosic materials. Of course, the hydroxyl group containing material is also substantially free of groups that may be thermally or photolytically unstable; that is, the material will not decompose or liberate volatile components at temperatures below about 100° C. or in the presence of actinic light that may be encountered during the desired polymerization conditions for the photo-copolymerizable composition.

Representative examples of suitable hydroxyl group containing materials having a hydroxyl functionality of 1 include alkanols, monoalkyl ethers of polyoxyalkyleneglycols, monoalkyl ethers of alkylene-glycols, and others known in the art.

Representative examples of useful monomeric polyhydroxy organic materials include alkylene glycols (e.g., 1,2-ethanediol; 1,3-propanediol; 1,4-butanediol; 1,6-hexanediol; 1,8-octanediol; 2-ethyl-1,6-hexanediol; bis(hydroxymethyl)cyclohexane; 1,18-dihydroxyoctadecane; 3-chloro-1,2-propanediol); polyhydroxyalkanes (e.g., glycerine, tri-methylolethane, pentaerythritol, sorbitol) and other polyhydroxy compounds such as N,N-bis(hydroxyethyl)benzamide; 2-butyne-1,4-diol; 4,4-bis(hydroxymethyl)diphenylsulfone; castor oil; and the like.

Representative examples of useful polymeric hydroxyl group containing materials include polyoxyethylene and polyoxypropylene glycols, and particularly the polyoxyethylene and polyoxypropylene glycol diols and triols having molecular weights from about 200 to about 10,000 corresponding to a hydroxy equivalent weight of 100 to 5000 for the diols or 70 to 3300 for triols; polytetramethylene ether glycols such as polytetrahydrofuran or “poly THF” of varying molecular weight; copolymers of hydroxypropyl and hydroxyethyl acrylates and methacrylates with other free radical-polymerizable monomers such as acrylate esters, vinyl halides, or styrene; copolymers containing pendent hydroxy groups formed by hydrolysis or partial hydrolysis of vinyl acetate copolymers, polyvinylacetal resins containing pendent hydroxyl groups; modified cellulose polymers such as hydroxyethylated and hydroxypropylated cellulose; hydroxy-terminated polyesters; hydroxy-terminated polylactones, and particularly the polycaprolactones; fluorinated polyoxyethylene or polyoxypropylene glycols; and hydroxy-terminated polyalkadienes.

Useful commercially available hydroxyl group containing materials include the “TERATHANE” series of polytetramethylene ether glycols such as “TERATHANE” 650, 1000, 2000 and 2900 (available from du Pont de Nemours, Wilmington, Del.), polytetrahydrofuran with an average molecular weight of 250 (available from Sigma-Aldrich, St. Louis, Mo.), the “PEP” series of polyoxyalkylene tetrols having secondary hydroxyl groups such as “PEP” 450, 550 and 650; “BUTVAR” series of polyvinylacetal resins such as “BUTVAR” B-72A, B-73, B-76, B-90 and B-98 (available from Monsanto Chemical Company, St. Louis, Mo.); and the “FORMVAR” series of resins such as 7/70, 12/85, 7/95S, 7/95E, 15/955 and 15/95E (available from Monsanto Chemical Company); the “TONE” series of polycaprolactone polyols such as “TONE” 0200, 0210, 0230, 0240, 0300 and 0301 (available from Union Carbide); “PARAPLEX U-148” aliphatic polyester diol (available from Rohm and Haas, Philadelphia, Pa.), the “MULTRON” R series of saturated polyester polyols such as “MULTRON” R-2, R-12A, R-16, R-18, R-38, R-68 and R-74 (available from Mobay Chemical Co.); “KLUCEL E” hydroxypropylated cellulose having an equivalent weight of approximately 100 (available from Hercules Inc.); “Alcohol Soluble Butyrate” cellulose acetate butyrate ester having a hydroxyl equivalent weight of approximately 400 (available from Eastman Kodak Co., Rochester, N.Y.); polyether polyols such as polypropylene glycol diol (e.g., “ARCOL PPG-425”, “Arcol PPG-725”, “ARCOL PPG-1025”, “ARCOL PPG-2025”, ARCOL PPG-3025″, “ARCOL PPG-4025” from ARCO Chemical Co.); polypropylene glycol triol (e.g., “ARCOL LT-28”, “ARCOL LHT-42”, “ARCOL LHT 112”, “ARCOL LHT 240”, “ARCOL LG-56”, “ARCOL LG-168”, “ARCOL LG-650” from ARCO Chemical Co.); ethylene oxide capped polyoxypropylene triol or diol (e.g., “ARCOL 11-27”, “ARCOL 11-34”, “ARCOL E-351”, “ARCOL E-452”, “ARCOL E-785”, “ARCOL E-786” from ARCO Chemical Co.); ethoxylated bis-phenol A; propylene oxide or ethylene oxide-based polyols (e.g., “VORANOL” polyether polyols from the Dow Chemical Co.).

The amount of hydroxyl group containing organic material optionally used in the compositions of the invention may vary over broad ranges, depending upon factors such as the compatibility of the hydroxyl-containing material with the resin, the equivalent weight and functionality of the hydroxyl-containing material, the physical properties desired in the final cured composition, the desired speed of photopolymerization, and the like.

Blends of various hydroxyl groups containing materials are also contemplated in this invention. Examples of such blends include two or more molecular weight distributions of hydroxyl-containing compounds, such as low molecular weight (below 200), intermediate molecular weight (about 200 to 10,000) and higher molecular weight (above about 10,000). Alternatively or additionally, the hydroxyl-containing material can contain a blend of hydroxyl-containing materials having different chemical natures, such as aliphatic and aromatic, or functionalities, such as polar and non-polar. As an additional example, one may use mixtures of two or more poly-functional hydroxy materials or one or more mono-functional hydroxy materials with poly-functional hydroxy materials.

If present, component (E) is typically present in the composition in an amount up to about 10 wt.-% or up to about 15 wt.-% or up to about 20 wt.-%.

If present, typical ranges include from about 0 to about 20 wt.-% or from about 0 to about 15 wt.-% or from about 0 to about 10 wt.-%.

The compositions of the invention can also contain suitable adjuvants such as accelerators, inhibitors or retarders, absorbers, stabilizers, pigments, dyes, surface tension depressants and wetting aids, antioxidants, and other ingredients well known to those skilled in the art.

The amounts and types of each ingredient in the composition should be adjusted to provide the desired physical and handling properties before and after polymerization. For example, the polymerization rate, polymerization stability, fluidity, compressive strength, tensile strength and durability of the dental material typically are adjusted in part by altering the types and amounts of polymerization initiator(s) and, if present, the loading and particle size distribution of filler(s). Such adjustments typically are carried out empirically based on experience with dental materials of the prior art.

Typical adjuvants include pigments, colorants and/or dyes. Examples include titanium dioxide or zinc sulphide (lithopones), red iron oxide 3395, Bayferrox 920 Z Yellow, Neazopon Blue 807 (copper phthalocyanine-based dye) or Helio Fast Yellow ER. These additives may be used for individual coloring of the dental compositions.

Further additives, which can be added, include stabilizers, especially free radical scavengers such as substituted and/or unsubstituted hydroxyaromatics (e.g. butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether (MEHQ), 3,5-di-tert-butyl-4-hydroxyanisole (2,6-di-tert-butyl-4-ethoxyphenol), 2,6-di-tert-butyl-4-(dimethylamino)-methylphenol or 2,5-di-tert-butyl hydroquinone, 2-(2′-hydroxy-5′-methylphenyl)-2H-benzotriazole, 2-(2′-hydroxy-5′-t-octylphenyl)-2H-benzotriazole, 2-hydroxy-4-methoxybenzo-phenone (UV-9), 2-(2′-hydroxy-4′,6′-di-tert-pentylphenyl)-2H-benzotriazole, 2-hydroxy-4-n-octoxybenzophenone, 2-(2′-hydroxy-5′-methacryloxyethylphenyl)-2H-benzotriazole, pheno-thiazine, and HALS (hindered amine light stabilizers). Such adjuvants may optionally comprise reactive functionality so that they will be copolymerized with the resin.

There is no absolute need for these adjuvants to be present, so adjuvants might not be present at all. However, if they are present they are typically present in an amount of at least about 0.01 wt.-% or at least about 0.5 wt.-% or at least about 1 wt.-% with respect to the whole composition.

The adjuvants can be present in an amount up to about 25 wt.-% or up to about 20 wt.-% or up to about 15 wt.-% with respect to the whole composition.

The composition as described in the text of the invention may comprise the components in the following amounts:

-   -   Compound (A): from about 5 to about 70 or from about 10 to about         60 or from about 10 to about 45 or from about 10 to about 30         wt.-%,     -   Filler (B): from about 25 to about 90 wt.-% or from about 30 to         about 85 wt.-% or from about 40 to about 80 wt.-%,     -   Initiator (C): from about 0.1 to about 3 or from about 0.2 to         about 2 or from about 0.3 to about 1.8 wt.-%,     -   Polymerizable compound (D): from about 0 to about 65 or from         about 5 to about 55 or from about 10 to about 40 or from about         10 to about 25 wt.-%,     -   Softener (E): from about 0 to about 20 wt.-% or from about 0 to         about 15 wt.-% or from about 0 to about 10 wt.-%,     -   Adjuvant (F): from about 0 to about 25 wt.-% or from about 0.01         to about 20 wt.-% or from about 0.5 to about 15 wt.-%.         wt.-% with respect to the weight of the whole composition.

The curable composition of the invention can be obtained by combining (including mixing and kneading) the individual components of the composition, preferably under “safe light” conditions.

Suitable inert solvents may be employed if desired when providing the mixture. Any solvent may be used which does not react appreciably with the components of the inventive compositions. Examples of suitable solvents include acetone, dichloromethane, acetonitrile and lactones. A liquid material to be polymerized may be used as a solvent for another liquid or solid material to be polymerized.

The invention provides a composition which can be hardened in an acceptable time frame, e.g., less than about 120 seconds (s) or less than about 100 s or less than about 60 s, and to a sufficient depth using visible light source equipment already available in the dental office or electronics fabrication facilities.

The compositions of the invention are particularly well adapted for use as a wide variety of dental materials, which may be filled or unfilled. Such dental materials include direct aesthetic restorative materials (e.g., anterior and posterior restoratives), prostheses, adhesives and primers for oral hard tissues, sealants, veneers, cavity liners, orthodontic bracket adhesives for use with any type of bracket (such as metal, plastic and ceramic), crown and bridge cements, artificial crowns, artificial teeth, dentures, and the like. These dental materials are used in the mouth and are disposed adjacent to natural teeth. The phrase “disposed adjacent to” as used herein refers to the placing of a dental material in temporary or permanent bonding (e.g., adhesive) or touching (e.g., occlusal or proximal) contact with a natural tooth. The term “composite” as used herein in the context of a dental material refers to a filled dental material. The term “restorative” as used herein refers to a dental composite that is polymerized after it is disposed adjacent to a tooth. The term “prosthesis” as used herein refers to a composite that is shaped and polymerized for its final use (e.g., as a crown, bridge, veneer, inlay, onlay or the like) before it is disposed adjacent to a tooth. The term “sealant” as used herein refers to a lightly filled dental composite or to an unfilled dental material that is cured after it is disposed adjacent to a tooth.

When the dental material is applied to a tooth, the tooth can optionally be pre-treated with a primer such as dentin or enamel adhesive by methods known to those skilled in the art.

The dental compositions of the invention can be used for example, as artificial crowns, anterior or posterior fillings, casting materials, cavity liners, cements, coating compositions, mill blanks, orthodontic devices, restoratives, prostheses and sealants.

In a preferred aspect, the dental material is a dental filling material. The dental filling materials of the invention can be placed directly in the mouth and cured (hardened) in situ, or alternatively, may be fabricated into a prosthesis outside the mouth and subsequently adhered in place inside the mouth.

If the composition is a light curing composition, it can typically be characterized by at least one of the following parameters after hardening:

-   -   Flexural strength: at least about 70 MPa, or at least about 80         MPa, or at least about 100 MPa determined according to ISO 4049,     -   E-Modulus: from about 2 GPa to about 11 GPa, or from about 4 GPa         to about 10 GPa determined according to ISO 4049,     -   Depth of Cure: at least about 4 mm, or at least about 4.1 mm, or         at least about 4.6 mm determined according to ISO 4049.

If the composition is a chemical curing composition and can typically be characterized by at least one of the following parameters after hardening:

-   -   Flexural strength: from about 50 MPa to about 100 MPa, or from         about 70 MPa to about 90 MPa determined according to according         to ISO 4049,     -   E-Modulus: from about 0.4 GPa to about 2.0 GPa, or from about         0.5 GPa to about 1.9 GPa determined according to according to         ISO 4049,     -   Elongation at Break: at least about 10%, or at least about 11%,         or at least about 12% determined according to DIN 53455,     -   Impact Strength: at least about 8 kJ/m2, or at least about 10         kJ/m2, or at least about 12 kJ/m2 determined according to ISO         179-1.

The invention is also directed to the use of the inventive monomers or mixture of monomers for the production of a dental composition, the process of using comprising the steps of:

-   c) placing the dental composition comprising the monomer or mixture     of monomers according to formula (1) in contact with a tooth, -   d) hardening the composition.

The inventive dental composition is typically stored in a container until use. Depending on the initiator system chosen, various containers can be suitable.

If the dental composition is provided as a one-component system, it can be stored in a container having only one chamber such as a compule. The compule has typically a cylindrical housing with a front and a rear end and a nozzle. The rear end of the housing is usually sealed with a movable piston. Typically, the dental composition is dispensed out of the compule or container using an applier having a movable plunger (e.g. an application device having the shape of a caulk gun). Examples of suitable compules or containers are described in U.S. Pat. No. 5,624,260, EP 1 340 472 A1, US 2007/0172789 A1, U.S. Pat. No. 5,893,714 and U.S. Pat. No. 5,865,803, the content of which with regard to the description of compules or containers is herewith incorporated by reference.

Alternatively, if the dental composition is provided as a two-component system, it can be stored in a dual-chamber container or cartridge and is mixed before use.

Cartridges which can be used are described e.g. in US 2007/0090079 or U.S. Pat. No. 5,918,772, the disclosure of which is incorporated by reference. Cartridges which can be used are commercially available from SulzerMixpac AG (Switzerland).

Static mixing tips which can be used are described e.g. in US 2006/0187752 or in U.S. Pat. No. 5,944,419, the disclosure of which is incorporated by reference. Mixing tips which can be used are commercially available from SulzerMixpac AG (Switzerland).

Thus, another embodiment of the invention is directed to a kit of parts comprising at least two, three, four, five, six or more compositions differ from each other at least with respect to their colour. As outlined above, the compositions are typically stored in a container.

The container may comprise a housing having a front end with a nozzle and a rear end and at least one piston movable in the housing.

The volume of the container is typically in the range from about 0.1 to about 100 ml or from about 0.5 to about 50 ml or from about 1 to about 30 ml.

Like the dental composition, the kit of parts described in the present text is to be used in the dental field, in particular for producing dental materials, including dental restorative material. The dental composition and kit of parts are typically used for treating and/or repairing a tooth.

Certain embodiments of the invention are essentially free from low boiling solvents (e.g. boiling point below about 150° C. at ambient pressure). In this context “essentially free from” means that the content is typically below about 1 wt.-% or below about 0.5 wt.-% or below about 0.1 wt.-% with respect to the whole composition.

According to another embodiment, compound (A) of the composition does typically not comprise halogen atoms like F, Cl, Br or I. According to a further embodiment, compound (A) of the composition does typically not comprise an urethane, amide and/or carbonate moiety. According an another embodiment, compound (A) of the composition does typically not comprise atoms like S and/or Si. According to a further embodiment, the dental composition does typically not comprise bis-GMA.

The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. The invention is not limited to the embodiments disclosed herein.

EXAMPLES

Unless otherwise indicated, all parts and percentages are on a weight basis, all water is deionized water, and all molecular weights are weight average molecular weight. Moreover, unless otherwise indicated all Experiments were conducted at ambient conditions (23° C.; 1013 mbar). Moreover, nearly all process steps are conducted under an atmosphere of dry air:

Measurements Particle Size

If desired, the mean particle size can be determined using a commercially available granulometer (Laser Diffraction Particle Size Analysis Instrument, MASERSIZER 2000; Malvern Comp.) according to the instruction of use provided by the manufacturer.

Flexural Strength 1 (FS 1)

If desired, the measurement of the flexural strength can be carried out according to ISO 4049 using a universal testing machine (Zwick Z 010, crosshead speed 1 mm/min). The flexural strength is typically given in MPa.

Flexural Strength 2 (FS 2)

If desired, the measurement of the flexural strength can be carried out according to ISO 4049 using a universal testing machine (Zwick Z 010, crosshead speed 1 mm/min) with the only deviation of using a test specimen of the size 4×6×25 mm. The flexural strength is typically given in MPa.

E-Modulus 1 (E-M. 1)

If desired, the E-M 1 can be determined according to ISO 4049 and is given in [GPa].

E-Modulus 2 (E-M. 2)

If desired, the E-M 2 can be determined according to ISO 4049 with the only deviation of using a test specimen of the size 4×6×25 mm and is given in [GPa].

Elongation at Break (EB)

If desired, the EB can be determined according to DIN 53455 and is given in [%].

Impact Strength (1S)

If desired, the IS can be determined according to ISO 179-1 (Charpy) using un-notched specimens (test specimen size: 4×6×50 mm) and a 0.5 J pendulum. IS is given in [kJ/m²].

Depth of Cure (DoC)

If desired, depth of cure (i.e., cure depth) can be analyzed according to ISO 4049 by packing a paste sample into a cylindrical metal curing mould (8 mm deep, 4 mm diameter) and curing the sample for 40 s with an ELIPAR™ Trilight Standard (800 mW/cm²) (3M ESPE Company). The cured sample was removed from the mould and uncured paste was scraped off of the sample with a plastic applicator after less than about one minute of curing. Results were reported as the average of three replicates.

Refractive Index (n_(D) ²⁰)

If desired, the refractive index can be measured with a Kruess AR 4 D device (refractometer according to Abbe's measure principle). The refractive index is typically measured at 20.0° C. at a wavelength of 589 nm.

Viscosity (η)

If desired, the viscosity can be measured with a Haake RotoVisco RV1 device (rotor C60/1 for viscosities up to 8000 mPas or rotor C20/1 for viscosities above 8000 mPas together with stator P61). The viscosity is typically measured at 23.0° C. between two plane and parallel plates (i.e. stator and rotor). After activation and rectification of the system, the appropriate rotor is installed. Then the rotor is lowered and the distance between stator and rotor is adjusted to 0.052 mm (using Software RheoWin Pro Job Manager Software Version 2.94) for the viscosity measurement. Then the rotor is lifted and the material to be measured is given onto the stator (1.0 ml with rotor C60/1 or 0.04 ml with rotor C20/1). Without undue delay, the rotor is lowered into the preliminary adjusted measuring position. The material to be measured is tempered at 23.0° C. The shear rate for the measurement has to be adjusted to a value that the torque is at least 5000 μNm (therefore normally shear rates of 100, 200, 500, or 1000 s-1 are used depending on the viscosity of the material to be measured). The measurement is started and run for 60 s. The viscosity values (Pas) are recorded starting 20 s after the start of measurement and the mean value of the recorded values is given as viscosity.

Compositions Abbreviations

The name and/or structure of the components used are given in Table 1.

TABLE 1 BF₃* Borontrifluoride tetrahydrofurane adduct (CAS no. 462-34-0) THF BHT 2,6-Di-tert-butyl-4-methylphenol, 2,6-Di-tert-butyl-p-cresol, 3,5-Di-tert- butyl-4-hydroxytoluene (CAS no. 7637-07-2) BA4EO- MA

C. E. 2 b) BA2Ox- MA

C. E. 3 a) BA2EO- Ac

C. E. 4 m) CDGE

CPh

CPh- MA

E8 h) CPh-A

E19 j) CPh-Ac

E20 ab) CPh-DB

CPQ Camphorquinone (CAS no. 10373-78-1) n) DESMA Urethane methacrylate, cf. Example 1 on page 35 of WO 2009/006282 r) DPI-PF6 Diphenyliodonium hexafluorophosphate (CAS no. 58109-40-3) O) EDMAB Ethyl-4-dimethylaminobenzoate (CAS no. 10287-53-3) p) EH

EHGP

EHGP- MA

EHGP- A

EHGP- Ac

EHGP- DB

EHTEO

EHTEO- MA

EHTEO- A

EHTEO- Ac

EHTEO- DB

EHTGP

EHTGP- MA

EHTGP- A

EHTGP- AM

EHTGP- Ac

EHTGP- DB

EHTSO

EHTSO- MA

EHTSO- A

EHTSO- AM

EHTSO- Ac

EHTSO- DB

EO Ethylene oxide (CAS no. 75-21-8) ER

ERGP

ERGP- MA

E1 e) ERGP- A

E2 i) ERGP- Ac

E3 aa) ERGP- DB

ERTEO

ERTEO- MA

E10 f) ERTEO- A

ERTEO- Ac

E11 ERTEO- DB

E12 ERTEO

ERTEO- MA

E16 ERTEO- A

ERTGP- AM

ERTGP- Ac

E17 z) ERTEO- DB

ERTSO

ERTSO- MA

ERTSO- A

ERTSO- AM

ERTSO- Ac

ERTSO- DB

Filler 1 Spray dried zirconia silica filler, <1 μm, surface treated q) Filler 2 Ground strontium containing glass filler, <3 μm (Schott Glaswerke), surface treated w) Filler 3 Fumed silica (Wacker HDKH 2000) x) GAA Glacial acetic acid (CAS no. 64-19-7) GMA

GP

HQ Hydrochinone (CAS no. 75-21-8) HQME Hydroquinone methyl ether, 4-Methoxyphenol (MOP) (CAS no. 150-76-5) Ini 1 1-Benzyl-5-phenyl-barbituric acid s) Ini 2 tert-Butylperoxy-3,5,5-trimethylhexanoate t) Ini 3 Dibutylphenylethylammonium chloride u) Ini 4 Copper(II) bis(1-phenylpentan-1,3-dione) complex v) MA Methacrylic acid (CAS no. 79-41-4) MSA Methane sulfonic acid, 70% (CAS no. 75-75-2) NaERT Mono-Modal Dispersion of Silaned 15 nm Silica Nano-Particles within ERTEO-MA E21 EO-MA E25 Na2ER Mono-Modal Dispersion of Silianed 15 nm and within ERTEO-MA TEO- MA NaTTE Mono-Modal Dispersion of Silaned 15 nm Silica Nano-Particles within TTEO-MA E22 O-MA NaTTE Mono-Modal Dispersion of Silaned 15 nm Silica Nano-Particles within TTEO-AM E23 O-AM Na2TTE Bi-Modal Dispersion of Silaned 15 nm and 55 nm Silica Nano-Particles within TTEO-MA E24 O-MA PO Propylene oxide (CAS no. 75-56-9) PPh₃ Triphenylphosphane (CAS no. 2136-75-6) RDGE

RPh

RPh- MA

RPh- A

RPh- Ac

RPh- DB

SO Styrene oxide (CAS no. 96-09-3) TCD alcohol

T-A

C. E. 1 c) TEA Triethylamine (CAS no. 121-44-8) TEAA Triethylamine acetate, in situ generated by mxing TEA and a molar excess of GAA TGP

TGP- MA

E4 TGP-A

E5 TGP-Ac

TGP- DB

THF Tetrahydrofuran (CAS no. 109-99-9) TTEO

TTEO- MA

E6 g) TTEO- A

E7 k) TTEO- AM

E8 l) TTEO- Ac

TTEO- DB

E9 y) TTGP

TTGP- MA

E13 d) TTGP- A

E14 TTGP- Ac

E15 TTGP- DB

TTSO

TTSO- MA

TTSO- A

TTSO- Ac

TTSO- DB

C. E. stands for comparative example.

Synthesis Compound (A)

Compound(s) (A) can be prepared as follows:

General Procedure 1: Reaction of a Diol-Precursor Like e.g. TCD Alcohol with Epoxies (e.g. GP) Using e.g. TEAA as Catalyst

E.g. TCD alcohol and GP as the corresponding epoxy functional reagent/s are mixed while stirring with e.g. cyclohexane. E.g. 1.5 wt.-% of TEA and 1.5 wt.-% of GAA (with respect to the mass of the sum of all reactants, to form in situ 3.0 wt.-% of TEAA) are added while stirring. Then the mixture is heated while stirring to a temperature of about 70° C. until completion of the addition reaction (measured via 1H-NMR: no signals of residual epoxy groups were detected). Optionally, 3 to 5 wt.-% of MSA is slowly added while stirring and stirring is continued for about 60 min at about 70° C. Then the mixture is allowed to cool to room temperature while stirring. The crude reaction mixture is washed once with water, then extracted twice with 2N NaOH solution, then once washed with water, then dried over anhydrous Na₂SO₄. After filtration, the filtrate is again filtered through basic alumina. Then the solvent is stripped off in vacuum.

General Procedure 2: Reaction of a Diol-Precuror Like e.g. TCD Alcohol with Epoxy Containing Mixtures (e.g. EO in THF) Using BF₃*THF as Catalyst

E.g. TCD alcohol is diluted in anhydrous THF, then BF₃*THF is added while stirring. Gaseous EO is added while stirring so that the temperature of the reaction mixture does not exceed about 30-40° C. After completion of the EO addition stirring is continued at room temperature for about 30 min. 13 wt.-% of water (with respect to the sum of the amounts of the reactive educts) are added, after about 30 min while stirring 13 wt.-% of basic alumina is added, too. After additional about 60 min of stirring 13 wt.-% of a solution of sodium methanolate in methanol (30% in methanol) is added. Then the suspension is stirred at room temperature for about 12 h. After filtration the solvent is stripped off in vacuum.

General Procedure 3: Reaction of a Di-Epoxy Functional Precursor Like e.g. CDGE with an OH Acidic Reactant like e.g. Phenol Using e.g. Potassium tert-Butoxide (KOtBu) as Catalyst

E.g. Phenol is mixed with e.g. toluene and warmed while stirring to a temperature of about 50° C. E.g. 3.0 wt.-% of KOtBu are added while stirring and stirring is continued until KOtBu is dissolved. At a temperature of about 80° C. CDGE is added while stirring so that the temperature does not exceed about 90° C. After completion of the addition the reaction mixture is stirred at a temperature of about 80° C. until completion of the addition reaction (measured via ¹H-NMR: no signals of residual epoxy groups were detected). Toluene is added while stirring. Then the mixture is allowed to cool to room temperature while stirring. The crude reaction mixture is extracted at least twice with 4N NaOH solution, then once washed with water, then dried over anhydrous Na₂SO₄. After filtration, the filtrate is again filtered through basic alumina. Then the solvent is stripped off in vacuum.

General Procedure 4: Esterification of Diol Based (e.g. TCD Based) Non Methacrylate Functional Intermediates with e.g. Methacrylic Acid (MA)

To the corresponding e.g. TCD based non-methacrylate functional intermediate in e.g. hexane BHT, HQME, optionally methylene blue, e.g. MSA as catalyst and e.g. MA are added. At reflux water is removed using a Dean Starck apparatus. After completion of the reaction the crude reaction mixture is extracted at least twice with 4N NaOH solution, then once washed with water, then dried over anhydrous Na₂SO₄. After filtration, the filtrate is again filtered through basic alumina. 100 ppm of BHT and 100 ppm of HQME are added to the filtrate. Then the solvent is stripped off in vacuum while air is bubbling through the crude sample.

General Procedure 5: Dispersions of Silaned SiO₂ Nano Particles Within the Described Diol Based (e.g. TCD Based) Monomers via a Slurry Silanation Procedure of SiO₂ Nano Particles

Dispersions of surface-modified, nano-sized silica were prepared e.g. in the corresponding e.g. TCD based monomer/s. The nano-sized silica particles can be surface-treated and dispersed within the curable resin as described in U.S. Pat. No. 6,899,948 B2, incorporated herein by reference. A preferred method of surface-treating and dispersing is described in Example 3, column 32, rows 31 to 42, as summarized below. The desired amount of the surface-modifying agent(s) are added to methoxypropanol and mixed. This alcohol solution is added to a silica sol slowly with swirling (1-2 minutes) and maintained at a temperature of about 80° C. for about 16 h. The surface-modified silica sol is solvent exchanged by mixing the sol with the corresponding e.g. TCD based monomer/s and heating the modified organic sol in an oven at about 85-90° C. for about 4 h. As is understood by one of ordinary skill in the art, such a procedure can be used with a wide variety of silica sols including those described herein, including sodium and ammonium stabilized silica sols. Also, other solvents such as ethanol, n-propanol and/or iso-propanol could be used instead of or with methoxypropanol. This process is also suitable for a wide variety of surface-modifying agents, including both reactive and non-reactive surface modifying agents. This process is also not limited by the resin into which the surface-modified nanoparticles are dispersed. Finally, process modification may also be used. For example, in some embodiments, the lower temperatures and the use of a vacuum can be desirable. For example, a surface-modified silica sol could be solvent exchanged by mixing the sol with the corresponding e.g. TCD based monomer/s and the modified organic sol could then be processed by applying a vacuum and heating in an oven at about 40 to 60° C. until completion.

Synthesis of ERGP-MA Inventive Example 1

According to General Procedure 1 116 g of ER, 172 g of GP were reacted using THF as solvent and KOtBu as catalyst. 239 g of ERGP (479 mmol, 82%) were isolated as yellowish liquid. According to General Procedure 4 157 g of ERGP, 81.4 g of MA, 30.0 mg of BHT, 80.0 mg of HOME, and 11.5 g of MSA were reacted using toluene as solvent. 76.4 g of ERGP-MA (120 mmol, 38%) were isolated as yellowish oil: η=9.4 Pa*s, n_(D) ²⁰=1.542.

Synthesis of ERGP-A Inventive Example 2

According to General Procedure 1 116 g of ER, 172 g of GP were reacted using THF as solvent and KOtBu as catalyst. 239 g of ERGP (479 mmol, 82%) were isolated as yellowish liquid. According to General Procedure 4 165 g of ERGP, 71.5 g of Acrylic Acid (AA), 28.0 mg of BHT, 77.0 mg of HOME, and 6.50 g of MSA were reacted using toluene as solvent. 172 g of ERGP-A (284 mmol, 86%) were isolated as yellowish oil: η=18.8 Pa*s, n_(D) ²⁰=1.547.

Synthesis of ERGP-Ac Inventive Example 3

According to General Procedure 1 116 g of ER, 172 g of GP were reacted using THF as solvent and KOtBu as catalyst. 239 g of ERGP (479 mmol, 82%) were isolated as yellowish liquid. According to General Procedure 4 60.0 g of ERGP, 24.9 g of Acetic Acid Anhydride (AAA) were first reacted using toluene as solvent, then 630 mg of para-Toluene Sulfonic Acid (pTSA) were added and water was removed. 48.6 g of ERGP-Ac (84.0 mmol, 69%) were isolated as yellowish oil: η=22.6 Pa*s, n_(D) ²⁰=1.540.

Synthesis of TGP-MA Inventive Example 4

According to General Procedure 1 100 g of TCD alcohol, 153 g of GP were reacted. 255 g of TGP (512 mmol, 100%) were isolated as yellowish liquid. According to General Procedure 4 70.0 g of TGP, 79.0 g of AA, 18.0 mg of BHT, 49.0 mg of HQME, 36.0 mg of methylene blue, and 3.52 g of MSA were reacted. 54.8 g of TGP-MA (188 mmol, 60%) were isolated as yellowish liquid: η=1.0 Pa*s, n_(D) ²⁰=1.520.

Synthesis of TGP-A Inventive Example 5

According to General Procedure 1 100 g of TCD alcohol, 153 g of GP were reacted. 255 g of TGP (512 mmol, 100%) were isolated as yellowish liquid. According to General Procedure 4 100 g of TGP, 42.0 g of AA, 17.0 mg of BHT, 46.0 mg of HQME, and 6.80 g of MSA were reacted using cyclohexane as solvent. 97.0 g of TGP-A (160 mmol, 80%) were isolated as yellowish oil: η=12.0 Pa*s, n_(D) ²⁰=1.521.

Synthesis of TTEO-MA Inventive Example 6

According to General Procedure 2 300 g of TCD alcohol, 64.6 g of EO, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 429 g of TTEO were isolated as colorless oil. According to General Procedure 4 213 g of TTEO, 161 g of MA, 44.8 mg of BHT, 121 mg of HQME, 89.6 mg of methylene blue, and 12.8 g of MSA were reacted using hexane as solvent. 237 g of TTEO-MA (67%) were isolated as colorless liquid: η=0.1 Pa*s, n_(D) ²⁰=1.499.

Synthesis of TTEO-A Inventive Example 7

According to General Procedure 2 300 g of TCD alcohol, 64.6 g of EO, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 429 g of TTEO were isolated as colorless oil. According to General Procedure 4 119 g of TTEO, 83.7 g of AA, 24.3 mg of BHT, 65.8 mg of HQME, 48.6 mg of methylene blue, and 9.76 g of MSA were reacted using hexane as solvent. 142 g of TTEO-A (88%) were isolated as colorless liquid: η=0.2 Pa*s, n_(D) ²⁰=1.503.

Synthesis of TTEO-AM Inventive Example 8

According to General Procedure 2 300 g of TCD alcohol, 64.6 g of EO, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 429 g of TTEO were isolated as colorless oil. According to General Procedure 4 first 230 g of TTEO, 57.8 g of MA, 39.7 mg of BHT, 107 mg of HQME, 79.3 mg of methylene blue, and 15.9 g of MSA were reacted using hexane as solvent and then additional 72.5 g of AA were added and the resulting mixture further reacted. 263 g of TTEO-AM (94%) were isolated as colorless liquid: η=0.2 Pa*s, n_(D) ²⁰=1.502.

Synthesis of TTEO-DB Inventive Example 9

According to General Procedure 2 300 g of TCD alcohol, 64.6 g of EO, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 429 g of TTEO were isolated as colorless oil. According to General Procedure 4 100 g of TTEO, 106 g of Benzoic Acid (BA), and 7.10 g of ?MSA were reacted using hexane as solvent. 135 g of TTEO-DB (80%) were isolated as colorless oil: η=3.8 Pa*s.

Synthesis of ERTEO-MA Inventive Example 10

According to General Procedure 2 179 g of ER, 38.9 g of EO, 700 g of THF, and 21.9 g of BF₃*THF were reacted. 338 g of ERTEO were isolated as colorless oil. According to General Procedure 4 304 g of ERTEO, 197 g of MA, 39.0 mg of BHT, 666 mg of HQME, and 10.0 g of pTSA were reacted using cyclohexane as solvent. 338 g of ERTEO-MA (83%) were isolated as colorless liquid: η=0.2 Pa*s, n_(D) ²⁰=1.500.

Synthesis of ERTEO-Ac Inventive Example 11

According to General Procedure 2 179 g of ER, 38.9 g of EO, 700 g of THF, and 21.9 g of BF₃*THF were reacted. 338 g of ERTEO were isolated as colorless oil. According to General Procedure 4 70.0 g of ERTEO, and 34.0 g of AAA were first reacted using toluene as solvent, then 770 mg of pTSA were added and water was removed. 77.8 g of ERTEO-Ac (88%) were isolated as colorless oil: η=0.3 Pa*s, n_(D) ²⁰=1.496.

Synthesis of ERTEO-DB Inventive Example 12

According to General Procedure 2 179 g of ER, 38.9 g of EO, 700 g of THF, and 21.9 g of BF₃*THF were reacted. 338 g of ERTEO were isolated as colorless oil. According to General Procedure 4 40.0 g of ERTEO, 52.9 g of BA, and 1.67 g of pTSA were reacted using toluene as solvent. 59.1 g of ERTEO-DB (87%) were isolated as colorless oil: η=4.5 Pa*s.

Synthesis of TTGP-MA Inventive Example 13

According to General Procedure 2 300 g of TCD alcohol, 221 g of GP, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 620 g of TTGP were isolated as colorless oil. According to General Procedure 4 150 g of TTGP, 93.3 g of MA, 24.7 mg of BHT, 434 mg of HQME, and 11.8 g of MSA were reacted. 139 g of TTGP-MA (70%) were isolated as colorless liquid: η=1.0 Pa*s, n_(D) ²⁰=1.515.

Synthesis of TTGP-A Inventive Example 14

According to General Procedure 2 300 g of TCD alcohol, 221 g of GP, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 620 g of TTGP were isolated as colorless oil. According to General Procedure 4 160 g of TTGP, 84.0 g of AA, 29.0 mg of BHT, 79.0 mg of HQME, 58.0 mg of methylene blue, and 11.7 g of MSA were reacted. 180 g of TTGP-A (89%) were isolated as colorless liquid: η=1.4 Pa*s, n_(D) ²⁰=1.517.

Synthesis of TTGP-Ac Inventive Example 15

According to General Procedure 2 300 g of TCD alcohol, 221 g of GP, 600 g of THF, and 37.9 g of BF₃*THF were reacted. 620 g of TTGP were isolated as colorless oil. According to General Procedure 4 50.0 g of TTGP, and 18.9 g of AAA were first reacted using toluene as solvent, then 510 mg of pTSA were added and water was removed. 55.0 g of TTGP-Ac (91%) were isolated as colorless liquid: η=1.7 Pa*s, n_(D) ²⁰=1.513.

Synthesis of ERTGP-MA Inventive Example 16

According to General Procedure 2 151 g of ER, 110 g of GP, 300 g of THF, and 19.0 g of BF₃*THF were reacted. 325 g of ERTGP were isolated as colorless oil. According to General Procedure 4 165 g of ERTGP, 65.0 g of MA, 28.0 mg of BHT, 75.0 mg of HQME, and 11.1 g of MSA were reacted. 155 g of ERTGP-MA (78%) were isolated as colorless liquid: η=1.1 Pa*s, n_(D) ²⁰=1.525.

Synthesis of ERTGP-Ac Inventive Example 17

According to General Procedure 2 151 g of ER, 110 g of GP, 300 g of THF, and 19.0 g of BF₃*THF were reacted. 325 g of ERTGP were isolated as colorless oil. According to General Procedure 4 70.0 g of ERTGP, and 31.5 g of AAA were first reacted using toluene as solvent, then 750 mg of pTSA were added and water was removed. 61.2 g of ERTGP-Ac (74%) were isolated as colorless liquid: η=1.5 Pa*s, n_(D) ²⁰=1.516.

Synthesis of CPh-MA Inventive Example 18

According to General Procedure 3 250 g of CDGE and 194 g of phenol were reacted. 367 g of CPh (825 mmol, 89%) were isolated as yellowish oil. According to General Procedure 4 128 g of CPh, 74.4 g of MA, 24.3 mg of BHT, 65.8 mg of HQME, and 5.65 g of MSA were reacted using cyclohexane as solvent. 70.0 g of CPh-MA (121 mmol, 42%) were isolated as yellowish liquid: η=4.2 Pa*s, n_(D) ²⁰=1.520.

Synthesis of CPh-A Inventive Example 19

According to General Procedure 3 250 g of CDGE and 194 g of phenol were reacted. 367 g of CPh (825 mmol, 89%) were isolated as yellowish oil. According to General Procedure 4 121 g of CPh, 59.0 g of AA, 21.6 mg of BHT, 58.5 mg of HQME, and 5.35 g of MSA were reacted using cyclohexane as solvent. 76.8 g of CPh-A (139 mmol, 51%) were isolated as yellowish oil: η=8.6 Pa*s, n_(D) ²⁰=1.524.

Synthesis of CPh-Ac Inventive Example 20

According to General Procedure 3 250 g of CDGE and 194 g of phenol were reacted. 367 g of CPh (825 mmol, 89%) were isolated as yellowish oil. According to General Procedure 4 70.0 g of CPh, and 32.2 g of AAA were first reacted using toluene as solvent, then 760 mg of pTSA were added and water was removed. 53.5 g of CPh-Ac (101 mmol, 64%) were isolated as yellowish oil: η=26.5 Pa*s, n_(D) ²⁰=1.512.

Synthesis of NaERTEO-MA (Mono-Modal Dispersion of Silaned Silica Nano-Particles within ERTEO-MA Inventive Example 21

According to General Procedure 5 116 g of ERTEO-MA, 200 g of Bayer Dispercoll S 4020, 9.38 g of 3-methacroyloxypropyltrimethoxysilane, 2.50 g of phenyltrimethoxysilane, and 388 g of ethanole were reacted. 201 g of NaERTEO-MA (95%) were isolated as yellowish gel.

Synthesis of Na2ERTEO-MA (Bi-Modal Dispersion of Silaned Silica Nano-Particles within ERTEO-MA Inventive Example 25

According to General Procedure 5 5.6 g of ERTEO-MA, 30.0 g of Bayer Dispercoll S 4020, 170 g of Bayer Dispercoll S 5005, 3.81 g of 3-methacroyloxypropyltrimethoxysilane, 3.04 g of phenyltrimethoxysilane, and 459 g of ethanole were reacted. 154 g of Na2ERTEO-MA (95%) were isolated as yellowish gel.

Synthesis of NaTTEO-MA (Mono-Modal Dispersion of Silaned Silica Nano-Particles within TTEO-MA Inventive Example 22

According to General Procedure 5 153 g of TTEO-MA, 300 g of Bayer Dispercoll S 4020, 14.4 g of 3-methacroyloxypropyltrimethoxysilane, 11.5 g of phenyltrimethoxysilane, and 581 g of ethanole were reacted. 270 g of NaTTEO-MA (88%) were isolated as yellowish gel.

Synthesis of NaTTEO-AM (Mono-Modal Dispersion of Silaned Silica Nano-Particles within TTEO-AM Inventive Example 23

According to General Procedure 5 94.2 g of TTEO-AM, 200 g of Bayer Dispercoll S 4020, 6.25 g of 3-methacroyloxypropyltrimethoxysilane, 4.99 g of phenyltrimethoxysilane, and 387 g of ethanole were reacted. 172 g of NaTTEO-AM (91%) were isolated as yellowish gel.

Synthesis of Na2TTEO-MA (Bi-Modal Dispersion of Silaned Silica Nano-Particles within TTEO-MA Inventive Example 24

According to General Procedure 5 136 g of TTEO-MA, 86.5 g of Bayer Dispercoll S 4020, 490 g of GraceDavison Ludox P-W50, 16.7 g of 3-methacroyloxypropyltrimethoxysilane, 13.3 g of phenyltrimethoxysilane, and 1.12 kg of ethanole were reacted. 385 g of Na2TTEO-MA (85%) were isolated as yellowish gel.

Synthesis of Light Curing One Component Compositions

Some of the compounds synthesized were used for producing a (dental) composition.

The compositions produced and tested with respect to their mechanical properties are given in Tables 2 and 3 below. In Tables 2 and 3 the values of the components a) to s) represent %-weight of the individual components in the corresponding dental formulation.

General Procedure A:

With magnetic stirring and under the exclusion of light the initiator system components were dissolved within the monomers at temperatures not above 50° C. (depending on the intrinsic viscosity of the used monomers).

General Procedure B:

According to General Procedure A the initiator system components were dissolved within the monomers. Under the exclusion of light and using a two-arm kneader the filler was mixed in portions with this mixture of initiator system and monomers. The amount of filler was manually determined depending on the desired handling properties of the dental composition. The dental composition was then light cured using a 800 mW halogen curing light (3M ESPE Elipar™ Trilight) and tested according to the corresponding measurements listed above. The respective values are given in Tables 2 and 3.

Dental Compositions A to E contain either of components a), b) or c) but not compound (A) according to the invention. In Tables 2 and 3 below, compound (A) is represented by components d) to l) and y) to ab). Thus, Dental Compositions A to E can be considered as comparative examples, whereas Dental Compositions F to L can be considered as inventive examples.

TABLE 2 Dental Composition A B C D E F G H a) 18.4 9.15 b) 17.7 8.60 c) 17.0 9.15 8.60 d) 17.7 e) 19.6 f) 18.4 g) h) i) j) k) l) m) n) 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 o) 0.19 0.19 0.19 0.19 0.19 0.19 0.19 0.19 p) 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 q) 81.3 82.0 82.7 81.4 82.5 82.0 80.1 81.3 r) s) t) u) v) w) x) y) z) aa) ab) FS 1  155 ± 15.0 137 ± 18.0  142 ± 10.0  153 ± 26.0  134 ± 9.00 82.0 ± 14.0  137 ± 14.0  126 ± 23.0 [MPa] E-M. 1 11.1 ± 0.20 11.7 0.20± 15.0 ± 0.30 13.5 ± 0.60 11.5 ± 0.40 8.50 ± 0.30 10.0 ± 0.30 7.60 ± 0.40 [GPa] DoC 4.65 4.74 5.34 5.60 5.57 4.67 4.81 4.93 [mm]

TABLE 3 Dental Composition I J K L a) b) c) d) e) f) g) 18.2 h) 21.1 i) 19.7 j) 20.5 k) l) m) n) 0.03 0.03 0.03 0.03 o) 0.19 0.19 0.19 0.19 p) 0.09 0.09 0.09 0.09 q) 81.5 78.6 80.0 79.2 r) s) t) u) v) w) x) y) z) aa) ab) FS 1 [MPa]  157 ± 10.0  114 ± 15.0 91.0 ± 8.00 72.0 ± 9.00 E-M. 1 [GPa] 8.60 ± 0.30 7.80 ± 0.30 2.70 ± 0.10 4.10 ± 0.30 DoC [mm] 4.12 5.65 5.20 5.85

As can be seen, compositions containing compound (A) according to the invention are superior with respect to certain properties compared to compositions not containing compound (A) according to the invention.

Synthesis of Chemical Curing Two Component Compositions

Some of the compounds synthesized were used for producing a (dental) composition.

The compositions produced and tested with respect to their mechanical properties are given in Tables 4, 5, 6, and 7 below.

In Tables 4 and 5 the values of the components a) to s) represent %-weight of the individual components in the corresponding dental formulation. In Tables 6 and 7 the values of the components Base 1 to CAT 5 represent relative % of the individual components in the corresponding dental formulation.

General Procedure C:

Under the exclusion of light the components listed in Tables 4 and 5 were mixed in a three-arm laboratory kneader. Residual agglomerates were homogenized in a ceramic three-roller mill.

General Procedure D:

The pastes listed in Tables 6 and 7 that were made according to General Procedure C were filled into the respective compartments of a 10:1 SulzerMixpac™ cartridge. The material was then applied into the respective metal moulds using a Garant™ II 10:1 cartridge equipped with a static mixer (SulzerMixpac Company). Cure was effected under pressure between plastic foil (Hostaphan™ RN75) and plexiglass plates for 1 h at 23° C. Then the press, plexiglass plates, and foil were removed, and the specimens within the moulds were subjected to post-cure at 36° C. under demineralized water for 23 h. The moulds were removed immediately before measurement. The cured specimens were tested according to the corresponding measurements listed above. The respective values are given in Tables 6 and 7.

Dental Composition—Base 1 contains either of components a), b) or c) but not compound (A) according to the present invention. In Tables 4 and 5 below, compound (A) is represented by components d) to l) and y) to ab). Thus, Dental Composition—Base 1 can be considered as belonging to a comparative example, whereas Dental Compositions—Base 2 to 6 can be considered as belonging to inventive examples.

TABLE 4 Dental Composition Base 1 Base 2 Base 3 Base 4 Base 5 Base 6 a) b) 52.4 c) d) 52.4 e) f) 52.4 g) 52.4 h) i) j) k) 52.4 l) 52.4 m) n) o) p) q) r) 13.1 13.1 13.1 13.1 13.1 13.1 s) t) u) 0.15 0.15 0.15 0.15 0.15 0.15 v) <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 w) 26.3 26.3 26.3 26.3 26.3 26.3 x) 8.00 8.00 8.00 8.00 8.00 8.00 y) z) aa) ab)

Dental Composition—CAT 1 contains component m) which is a component according to the state of the art, whereas Dental Compositions—CAT2 to CAT 5 contain either of components y), z), aa) and bb), components which fall within the definition of compound (A) according to the present invention.

TABLE 5 Dental Composition CAT 1 CAT 2 CAT 3 CAT 4 CAT 5 a) b) c) d) e) f) g) h) i) j) k l) m) 79.7 n) o) p) q) r) s) 10.0 10.0 10.0 10.0 10.0 t) 0.30 0.30 0.30 0.30 0.30 u) v) w) x) 10.0 10.0 10.0 10.0 10.0 y) 79.7 z) 79.7 aa) 79.7 ab) 79.7

Dental Composition M contains Base 1 and CAT 1, compositions which both contain components according to the state of the art. Dental Compositions N to V contain either a Base component containing a compound (A) according to the present invention or a CAT component containing a compound (A) according to the present invention. Thus, Dental Compositions N to V can be considered as inventive examples.

TABLE 6 Dental Composition M N O P Q R Base 1 90.9  Base 2 90.9  Base 3 90.9  Base 4 90.9  Base 5 90.9  Base 6 90.9  CAT 1 9.09 9.09 9.09 9.09 9.09 9.09 CAT 2 CAT 3 CAT 4 CAT 5 FS 2  102 ± 1.90 55.3 ± 6.10 55.1 ± 4.90 83.9 ± 3.10 90.4 ± 7.00 99.8 ± 9.60 [MPa] E-M. 2 2.07 ± 0.11 0.70 ± 0.16 0.48 ± 0.07 1.43 ± 0.03 1.55 ± 0.07 1.85 ± 0.25 [GPa] EB [%] 10.0 ± 1.20 15.4 ± 2.20 23.3 ± 2.80 13.8 ± 2.60 18.8 ± 2.90 10.2 ± 4.10 IS [kJ/m²] 7.40 ± 2.80 11.5 ± 2.20 16.6 ± 3.50 10.1 ± 0.70 16.9 ± 2.70 12.9 ± 3.40

TABLE 7 Dental Composition S T U V Base 1 90.9 90.9 90.9 90.9 Base 2 Base 3 Base 4 Base 5 Base 6 CAT 1 CAT 2 9.09 CAT 3 9.09 CAT 4 9.09 CAT 5 9.09 FS 2 88.3 ± 89.9 ± 83.8 ± 92.8 ± [MPa] 7.70 3.40 5.00 5.10 E-M. 2 1.81 ± 1.52 ± 1.70 ± 1.69 ± [GPa] 0.07 0.03 0.05 0.04 EB [%] 12.8 ± 11.8 12.0 ± 12.8 ± 0.70 1.60± 1.20 2.40 IS [kJ/m²] 11.1 ± 10.6 ± 11.1 ± 13.2 ± 0.70 2.40 4.40 2.40

As can be seen, compositions containing compound (A) according to the invention are superior with respect to certain properties compared to compositions not containing compound (A) according to the invention. 

1. A dental composition comprising a) compound (A) with the following features: only one backbone unit (U) with 6 to 20 carbon atoms, at least 6 carbon atoms thereof forming an aromatic or an aliphatic cyclic moiety, the remaining carbon atoms either being part of substituents pending from the cyclic moiety or being part of bridging groups to spacer units, wherein one or more of the remaining carbon atoms can be replaced by an oxygen atom, the backbone unit not comprising a bisphenol structure, one or two spacer unit(s) (S) being connected to the backbone unit (U) via an ether linkage, at least one spacer unit (S) comprising a —CH2-CH2-CH2-CH2-O—CH2-CH(Q)-OG chain or a —CH2-CH(OG)-CH2-OM residue or a mixture of these two types of spacers within one spacer unit, with G comprising at least one group selected from acroyl, methacroyl, acetyl, benzoyl, and combinations thereof, M comprising at least one aryl group, Q comprising at least one group selected from hydrogen, methyl, phenyl, phenoxymethyl, and combinations thereof, with the proviso that at least two G groups are present in compound (A), wherein in the case where only one spacer unit (S) is present, the G group not being part of said spacer unit (S) is located in a substituent pending from the aromatic or aliphatic cyclic moiety, compound (A) not comprising halogen atoms, b) filler (B) and c) initiator (C).
 2. The dental composition according to claim 1, wherein compound (A) is characterized by at least one of the following features: Molecular weight (Mw): from about 550 to about 1000; Reactive Functionality: 2 ethylenically unsaturated reactive groups per molecule attached via an ester linkage onto the backbone; Non Reactive Functions: 2 hydrocarbon non reactive groups per molecule attached via an ester linkage onto the backbone; Polar Groups: no free OH groups within the molecule; Secondary Network: no urethane moieties within the molecule; and Refractive index: from about 1.495 to about 1.565 (n_(D) ²⁰).
 3. The dental composition according to claim 1, wherein the backbone unit (U) comprises a moiety being selected from

wherein the symbol “*” indicates connecting points of the moiety.
 4. The dental composition according to claim 1, wherein the spacer unit(s) (S) comprises a moiety being selected from the group S1:

with m=1 to 3 and n=1 to 3, Q=hydrogen, methyl, phenyl or phenoxymethyl, S2:

with M=aryl or phenyl, and S3:

with m=1 to 3 and n=1 to 3, Q=hydrogen, methyl, phenyl or phenoxymethyl, and M=aryl or phenyl, wherein the symbol “*” indicates a connecting point of the moiety.
 5. The dental composition according to claim 1, wherein compound (A) is characterized by a structure according to any of formulas (I), (II), or (III)

with a, b=0 to 3, c, d=0 to 3, (a+b)=1 to 6, (c+d)=1 to 6, Q=being independently selected from hydrogen, methyl, phenyl and phenoxymethyl,

with a, b=0 to 3, c, d=0 to 3, (a+b)=1 to 6, (c+d)=1 to 6, Q=being independently selected from hydrogen, methyl, phenyl and phenoxymethyl, wherein G is selected from

and wherein U is selected from

and mixtures thereof, wherein the symbol “*” indicates a connecting point of the moiety.
 6. The dental composition according to claim 1, wherein compound (A) is selected from

and mixtures thereof.
 7. The dental composition according to claim 1, wherein initiator (C) comprises a redox initiator, a photo initiator or a mixture of both.
 8. The dental composition according to claim 1, comprising in addition one or more of the following components: a polymerizable compound (D) being different from compound (A) a softener (E) not comprising polymerizable group(s), an adjuvant (F).
 9. The dental composition according to claim 1 comprising a polymerizable compound (D) comprising at least one ethylenically unsaturated bond.
 10. The dental composition according to claim 1 comprising the components in the following amounts: Compound (A): from about 5 to about 70 wt.-%, Filler (B): from about 25 to about 90 wt.-%, Initiator (C): from about 0.1 to about 3 wt.-%, Polymerizable compound (D): from about 0 to about 65 wt.-%, Softener (E): from about 0 to about 20 wt.-%, Adjuvant (F): from about 0 to about 25 wt.-%, wt.-% with respect to the weight of the whole composition.
 11. The dental composition according to claim 1, being a light curing composition and being characterized by at least one of the following parameters after hardening: Flexural strength: at least about 70 MPa determined according to ISO 4049, E-Modulus: from about 2 GPa to about 11 GPa determined according to ISO 4049, Depth of Cure: at least about 4 mm determined according to ISO
 4049. 12. The dental composition according to claim 1 being a chemical curing composition and being characterized by at least one of the following parameters after hardening: Flexural strength: from about 50 MPa to about 100 MPa determined according to according to ISO 4049, E-Modulus: from about 0.4 GPa to about 2.0 GPa determined according to according to ISO 4049, Elongation at Break: at least about 10% determined according to DIN 53455, Impact Strength: at least about 8 kJ/m² determined according to ISO 179-1.
 13. The dental composition according to claim 1 being contained in a container.
 14. Kit of parts comprising at least 2 compositions according to claim 1, the compositions differing from each other at least with respect to their colour.
 15. The dental composition according to claim 1, wherein the dental composition is chosen from a dental cement, a crown and bridge material, a dental filling material, a casting material, a cavity liner, a coating compositions, a mill blank, an orthodontic devices, a sealant and combinations thereof. 